Shore Line

Technology, Nature, Software and Networks: Materializing the Post-Romantic Landscape

Abstract

I began making films and installations in the early 1970s. Although I have worked across a range of media, I have always concentrated on one particular theme that I conceptualise as a two-sided question: How do we see ourselves in relation to the natural world, and how should we position our selves and our technologies within it? This essay traces some of the threads of these seminal ideas through a selection of works made in the years between 1974 and 2009. I conclude with a detailed description of Tree Studies, a large-scale new media installation powered by real-time data from weather stations around the planet.

The term cybernetics comes from the Greek word kubernetes, meaning governor and steersman. It conjures up images of early sea voyagers in small wooden ships with oars and single sails, the most advanced technology of the ancient world. These sailors were dependent on their mastery of that technology and their ability to negotiate the hazards of uncharted oceans and unknown shorelines lying beyond the horizon of the known world. The image of piloting within a changeable and dynamic environment, then and now, is one of humans and their machines in an encounter with the vast and unpredictable world of nature. My rather single-handed voyage began auspiciously one day in 1970 when, acting on impulse, I strapped an 8mm camera to the wind vane self-steering gear on a friend’s sailing boat and let the wind direct my film.

Homeostasis
Many of my experimental films and all my new media projects are based on a cybernetic model, in which the relationship between technology and nature is articulated collaboratively between two interrelated systems, of which one is mechanistic and the other is not. I produced films such as Windmill (1973) and Seven Days (1974), for example that, were loosely based on the concept of homeostasis, where a system is able to regulate its internal stability while maintaining a dynamic equilibrium with its environment.

Dualisms
The original premise for these weather-driven works was primarily philosophical, grounded in a deeply felt love of landscape. The works were further informed by my rejection of dualism and of the technological domination and “enframing,” as Heidegger [1] called it, of nature, that was characteristic of the Enlightenment period. The socioeconomic costs of climate change are becoming part of everyday experience, the ideas that have informed my practice for the last 40 years have become charged with a renewed sense of practical urgency. The idea of an ontological shift in the way we see ourselves in relation to nature is no longer a matter of abstract speculation. This essay attempts to position my work in relation to some of these long-overdue changes in human perception.

Experimental Film
My art practice was heavily influenced by Structural Materialist film theory at the London Film Makers Co-operative (LMFC) [2] and by cybernetic and systems theory as encountered at the Slade School of Fine Art, where, as a graduate student and subsequently as a faculty member, I came into contact with some of the pioneers of interactive technology and computer-driven art forms. In most of my 16mm films, I devised location specific strategies whose purpose was to establish and maintain a readable and direct “indexical” registration of natural phenomena within the filmic image. Natural processes were not simply recorded from the outside, as if by an objective observer; but were through the sensuality of landscape imagery, but at the same time, the image includes a visual record of the material nature of the representational process. The cinematic experience is thus based on the interdependence of these two representations, which together, produce the “shape” and “content” of the representational system as a whole.

Although structural filmmakers on both sides of the Atlantic [5] began experimenting with landscape imagery in the 1970s, the landscape in these films was usually of secondary importance. As in mainstream narrative cinema and Renaissance painting, where nature is the backdrop to the human drama, the emphasis remained primarily on human activity upon the process of filmmaking and the construction of the viewer experience. It seemed to me that in most of these works, the system used to construct the film and the system operating in the landscape were disconnected and still split from the world along Cartesian lines, with the landscape positioned, as it is in fiction film and shampoo commercials, firmly in the background.

A love of landscape and an interest in the scientific investigation of complex systems pushed my practice in a very different direction from that of my contemporaries. What interested me about both structural film and complex systems theory was the possibility of creating work based on the interconnectedness of these systems, work where landscape was not secondary to the filmmaking process or the filmmaking process to landscape, but process and structure, as revealed in both, could carry information and communicate ideas.

In all my films and installations I use the simple structuring capabilities of moving-image technologies, such as variable-frame rate, in-camera editing and multiple projection, in combination with natural phenomena such as wind and tides and the rotation of the planet, to produce works in which mind, technology and nature are not experienced as separate things divided along Cartesian lines but as interconnected parts of one larger, dynamic system.

Seven Days

Seven Days 1974 16mm film, 20 mins.

In Seven Days (1974) (Fig. 1), the shape of the film is the result of the interaction between the filmmaker, the equipment, the rotation of the planet and the weather. The camera is aligned with the sun and pans at the same speed as the earth, recording one frame per second from sunrise to sunset. Cloud cover and the sun’s visibility thereby determine the appearance of the images recorded by the system. The final shape of the film is a consequence of the interaction between the more predictable, mechanistic aspects of technology and the less predictable variables of the natural world.
A similar theme emerges in Park Film (1972), where the overall pacing is determined by the flow of people along a busy park pathway in London. The flow is determined by the commuter clock—morning and evening rush hours and by the weather; on a stormy day walking home across the park is considerably less attractive than catching a bus. This is not really a film about a park, or a record of the people passing through the park. The camera is an active observer, for as passersby move through the field of view, so the filmmaker triggers the shutter, making them active participants, along with the camera, the filmmaker and the weather, in the interaction between a park and the city that surrounds it, a process of interaction that shapes the film.
The overall shape created in Park Film, and also in Seven Days, may be described as an emergent property, a result of the continuous interplay between the cinematic process and the environment.
Technology and Language
The use of technology in my practice is inseparably connected to language. Anthropological research has produced evidence to suggest that tool-making and language appeared around the same time in history and that syntax was possibly a byproduct of more complex tool-making procedures [6]. For instance, when I engineer the wind to crank the camera shutter in my films and installation, such as c Anemometer [1974] or use a device to align the camera with the rotation of the earth as in Seven Days, I am dealing not only with tools but also with the language of abstract forms and material processes. These material elements of the films’ construction function as syntactic devices that are inseparably connected to the meaning of the work. This typology also applies to my gallery installations.

Bringing the landscape into a gallery is rather like making a map. The difficulty of representing the limitless expanse of a landscape in the geometric architectural space of the gallery is conceptually similar to the difficulty experienced by the cartographer who uses the Mercator projection to translate the curvature of the earth onto the flat surface of a chart. In my installations, the process of translation is not the gallery.

In the installations, as with the films, both the material process of representation and the landscape imagery are crucial to the reading of the work. The image-recording process in the installations is usually quite simple, often a single, carefully positioned and continuous “take” or recording. However, the projection equipment used to present the work in the gallery becomes the focus of attention in the installation rather than mechanics and positioning of the camera.

Shore Line
Fig 1. Shore Line 1976 16 mm. Six projector gallery installation. ACME Gallery London UK

In Shore Line (1977), for example, a line of six noisy 16mm projectors is prominently mounted on white plinths: Like an opposing army, they face an image of a pristine line of surf breaking on a sandy beach (Fig. 2). The prominence of the projectors, the visibility of the film loops strung from the ceiling, the shadows of the gallery visitor cast on the screen and the noise of the projectors there is no other soundtrack seen and heard together with the composite image of the beach create a model in which meaning.


Fig 2. Changing Light 2004 Interactive digital media installation. Artspace Gallery Sydney Australia

Changing Light (2004) builds on the model of interactivity that I used in Park Film. In this installation, motion sensors hooked up to a computer system respond to the movement of people in the gallery (Fig. 3). This directly affects the image of the surface of a lake projected on a horizontal screen suspended just above floor level. The DVD recording has eight distinct tracks or “chapters,” corresponding to the eight takes of original footage. The “chapters” are programmed to alternate in relation to the movement and presence of participant/viewers in the gallery space. In this installation, “nature,” as represented by the lake, is not seen to be separate from the technology that reproduces it or the people who observe it. The viewer is invited to participate in a model in which nature and technology are seen to be one and the same

At Sea-Structural Film and the Santiago Theory of Cognition
In At Sea (2007), I used digital technology to produce an imaginary landscape rather like a chart or map, complete with landfalls, lighthouses, channel beacons and endless expanses of fog and featureless ocean. However, there are no fixed points on this map, and any attempt at spatial orientation is made impossible by the relentless shifting of a few ephemeral coordinates. My intention was not to create a panorama, a view or a depiction of homogeneous space but to create instead an internal topography.

The Santiago Theory as revealed in the writings of Humberto Maturana in the 1970s provided me with a framework for thinking about this idea [7]. The authors of the Santiago Theory propose, “The world everyone sees is not the world but a world which we bring forth with others” [8]. In this model of reality, the world, Kant’s Ding an sich (thing in itself) corresponds to “the world” beyond that which is known by our senses. He argues that this realm, which he distinguishes from known phenomena, is not readily available to human perception. [OK] “The world everyone sees is not the world but a world which we bring forth with others” [8]. In this model of reality, the world—Kant’s Ding an sich (thing in itself)“the world” beyond that which is known by our senses, is not readily available to human perception. It would seem that our perceptions are designed specifically to screen out all but the most ‘essential’ information and that our only knowledge of the world is derived from the internal representation that is continuously being constructed by the cognitive processes that connect our conceptual map to the territory. In both the Santiago Theory and Structural Materialist film theory, the emphasis is placed on the conscious awareness of representation as process rather than the representation as such.

In the digital media installation At Sea, both myself, as artist/ video maker, and the viewer participate in the creation of a fictional seascape, in the representation of a subject that is too large to be apprehended in its entirety. The viewer is indeed ‘at sea’ and has the choice to either try and piece together fleeting events track of time and space. Based on my own experience I imagine that a patient viewer will alternate between these two states while following the drift of his or her own thoughts and reveries. It is my hope that this ‘bringing forth’ of an unknowable subject, in this case the incomprehensible vastness of the ocean, may be read both literally and as a metaphor for the process of cognition itself.

Reverie
My installations do not bombard the viewer with frenetic action, rapid jump cuts or byte loads of information. I prefer to give the viewer the time and the space to consciously engage with the moving image, with its production and with its presentation. With this in mind, I endeavor to create installations in which the viewers are encouraged to slow down, to take back control of their own thoughts and perceptions, to forget about the constraints of beginnings, middles and ends, entering instead a state of mind in which reverie and contemplation can play a creative role in the process of conscious thought. It is my hope that in such a space it may still be possible to consider our selves and our technologies, not only in relation to any particular landscape but also in relation to the larger more inclusive body of the planet as a whole.

The Visual Clock Project 2007-2107
Introduction

The Visual Clock project includes a series of three related works made in collaboration with Vancouver based media artist Brady Marks. All three projects: Taking Time (2007-8) Time After-(2010) and The Doomsday Clock (work in progress), use digital technology to slow down the recording of a photographic image.

The world’s first photograph,was probably taken by Joseph Niépce in 1826, near Chalon-sur-Saône. The exposure time for the photograph, View from the Window at le Grace, is believed to have been between 8 consequence of these shortcoming perhaps, the history of photography has since been marked by the pursuit of ever-faster shutter speeds. There is no doubt that photography has taught us how to see the world in a different way, and whilst making these works I ask the question: what would photography look like if technological developments had concentrated on slowing the imaging process down instead of speeding it up? What would this photography reveal about the relationship between the high-speed lives of 21st Century human beings and the vast time scales of the natural world?

The Visual Clock series uses digital technology to slow down the process of image recording in order to reverse the usual object/ground relation and re-position human activity within the daily cycle of tide and weather. The system is capable of producing a single photographic image containing a visual record of the changing seasons, and potentially, the long-term impact of climate change.

Technical overview
In all of the Visual Clock projects, a high-resolution web cam relays a real-time image via computer, to a wall–mounted LCD monitor. Instead of using the lines and frames of the video image, the picture is continually updated, one pixel (or cluster of pixels) at a time, in random order. In this way, the recording of the photographic image can be massively slowed down without blurring or other deterioration in image quality. The sharply focused image is neither a still photograph, nor a movie video image, and yet it represents, at any given moment, an accurate trace of time present as well as time past. The pixels are not static, as they are in a conventional movie or photographic image, but flicker luminously as they refresh evenly across the surface of the monitor. Unlike a conventional photographic image, the picture is never complete but updated continuously, recording every nuance of changing light and movement within a single frame. Like the brush strokes on an Impressionist canvas, each pixel, or group of pixels, represents a single passing moment. To the computer, time passing is just a series of repetitive actions, whereas to our human perceptions, the pixels flickering on the monitor screen are like so many tiny windows on a

The Projects
Taking Time (2007-8): The Silver Bay General Store and Coffee Shop, Gabriola Island, BC Canada. The work ran continuously for a period of eight months and was relayed live to the online web site of the Gabriola Island ” Elements festival” (www.elelemtnsfestival.ca).

The web cam was located in the Silva Bay General Store and pointed South-east, across the waters of the picturesque harbor outside. The image, displayed on a single monitor, duplicated the view through the windows, which served as a constant reference to the real time events outside. The refresh rate for the image was set at about twenty minutes and, at that speed, human activity barely registered. However, changes in light, weather conditions and even tidal levels were clearly visible. There is no finite recorded image and what may have been seen on the monitor screen will remain as ephemeral as the light which dance still on the waters of Silva Bay.

Time After -(2010) Interurban Gallery, Vancouver Canada
The work used web cam, located on the roof of a twenty–story hotel, which observed a busy urban street with the working port of Vancouver and the snow–capped mountains beyond. This visual data was relayed to a series of five computers, which were programmed to feed a five–monitor display using the same sort of software as Taking Time. In this version of the project, the series of five monitors were mounted in a horizontal array, with each monitor displaying a different version of the same web cam image. The monitors resembled the hours, minutes and seconds panels of a digital clock face. On the monitor to the left, the image of the city was updated roughly 5 pixels at a time, with a total refresh rate of 1 minute. The monitor located immediately to its right used the same software, but here the process of image replenishment took place in 10-minutes. The next monitor in the line refreshed every 100 minutes, the next one every 1,000 minutes and the fifth, every 10,000 minutes. Human activity was clearly visible in the first monitor on the left, less visible on the second monitor, and by the third monitor from the left, people had all but disappeared, leaving the changing weather and light to play in the deserted streets. The fourth and fifth monitors from the left contained pixels recorded during both the day and during the night, and the whole clock-like structure rolled relentlessly forward as the exhibition continued.

Time After

Fig 3 Time After -2010 Web Cam and digital media installation. Interurban Gallery, Vancouver Canada.

The Doomsday Clock (2010-) Location TBA. A work in-progress.

This third project in the Visual Clock series is still in the planning stage. It is intended to be a visual counterpart to the 100year performance of John Cage’s ASAP currently under way in the town of Halberstadt, Germany. The piece is, in part, a response to some of the more alarming predictions currently issuing from the scientific community. As the title perhaps flippantly suggests, this version of the Visual Clock project, is intended to address climate change and even the fate of humanity. The location for the Doomsday Clock project has not yet been decided at this time, but it will probably be located on a rooftop in the downtown area of the City of Vancouver. In this iteration of the Visual Clock concept, I would like single photographic image. Assuming that there will be anyone around to observe the image in the year 2110, time past would indeed be embedded in time present and the ongoing process of pixel replenishment would potentially bear witness to the catastrophic changes predicted for the years to come.

Tree Studies

Fig 4. Tree Studies 2006. Digital media installation. Gwangju Biennale South Korea

Tree Studies 2006. A moving image installation driven by global weather
In Tree Studies, a custom software component designed by Brady Marks selects from three pre–recorded film sequences, each of which shows a tree from a different viewpoint. The material is edited in real time, as the various components of the system respond to wind speed and wind direction as measured by weather stations located on four different continents. The weather data is transmitted to the installation via a high-speed Internet connection, allowing the thermal energy produced by the rotation of the earth, the heating and cooling effect of day and night to drive the installation. Combining the speed and versatility of the Internet with the energy that drives our planetary climate, Tree Studies proposes an environmental model in which technology works collaboratively with natural forces on a global scale.
Technical Overview. There are five main components to the Tree Studies installation: (1) remote and local wind sensors; (2) a software component that processes incoming data; (3) a software component that edits and mixes sound and image; (4) projection and sound system in the gallery; (5) a display console. The four weather stations provide the data used to drive the three-channel image display, sound mix and console. The software component searches for the highest wind speed among the four weather stations. The open source software sub-component has been developed to communicate with the selected weather station via the Internet, using the serial link to then relay back the wind speed and direction data to the Max/MSP display components.
The netsend/receive open source Max/MSP externals are used to complete this relay system. The software component utilizes the Jitter/Max/MSP programming environment to display, animate and cut back and forth between the three streams of footage in response to the weather data, automatically detecting significant changes in wind direction and responding by cutting to the appropriate viewpoint selected from the digitized film footage.

Tree Studies console display
Fig 5 Tree Studies: console display

The image produces three discrete high-definition video signals, each projected onto one of three walls of the hexagonal gallery space, with each projection representing a different viewpoint of the tree. A second output registers the incoming data on a graphic display panel, which resembles a series of compass cards, one for each weather station and a fifth, which registers the output to the projection system.
The Image: The stark, expressive form of a large leafless tree was filmed against a background of changeable stormy winter skies. The horizon line was positioned low down in the picture plane; in the background, low wooded hills recede into the distance, and in the lower foreground a slope of dry, frost-bleached grass leads the eye towards the distant woods. The scene is of life clinging to the damp warmth of the earth in the cold twilight of the northern winter.
Shooting Strategy: The footage of the tree was shot in three separate takes, each one taken at a different angle to the tree. The camera was positioned at 15<deg> increments along the radius of a 45<deg> arc. The footage was shot over a period of several hours using time-lapse photography to emphasize the changing visual relationship between the tree branches and the cloudy sky. The aperture setting was randomized from frame to frame to increase the exposure range,(latitude) and create a flicker effect when projected at slower frame rates.
Sound. The sound mix, like the images, was driven by real-time input from the weather. The ingredients of the mix include distant human voices, bird cries (starling and raven), wind sounds, a passing aircraft and the simulated harmonics of an Aeolian harp created by a specially written program. In the installation, input from the weather stations tends to push the system toward instability, causing it to constantly create new and unexpected combinations from the same set of sonic components by re-mix the audio tracks and spatially re-position the elements of the mix within the eight track soundscape.
The Interactive System and Installation: The gallery space for Tree Studies [10] was hexagonal, with each side measuring about 8 m across (Fig. 5). The three walls opposite the entrance door were used to sound, with one speaker placed in each of the six corners of the space (Fig. 6). In addition, a series of 12 light-emitting diode floor lights was placed at regular intervals around a circle. These lights were used to indicate the changing wind direction at whichever weather station was[OK?] online.
The system operated like a wind-powered edit suite, with wind speed and direction “deciding” which video channels were projected from one moment to the next. In this way, the technology worked in collaboration with the wind to create a visual dance about the central axis of the tree, mapping a 3D representation of space and time in the winter landscape onto the three projection screens in the gallery (Fig. 7). Wind speed acceleration and deceleration also balanced the multi-channel sound mix and triggered a variety of sound events, such as the sounds of swarming starlings, an Aeolian harp and distant human voices.
In addition, fluctuations in wind speed caused the footage to speed up and slow down. Clouds, light and the movement of people consequently appeared in ‘gusts’. For example, if the wind stopped blowing, the footage would appear to hover indecisively, going back and forth over three or four frames until another gust of wind from somewhere on the planet drove the faltering scene forward again. People walking through the landscape appeared to be blown along the pathway like so many autumn leaves on a blustery day. The software also sent the weather data to a console with a graphic display representing the wind speed and direction at the four locations (Fig. 8).
Some viewers were content with the visceral experience of the wind-swept tree. Others chose to reference the console, discovering a second level of meaning embedded within the system as a whole..
Concluding Thoughts
The image of the tree is a powerful symbol reminding us that both the fragility and the strength of all living systems are determined by our ability to exist in dynamic equilibrium with the environment. The tree carries symbolic meaning in many cultures but is perhaps most significant in the Buddhist traditions, in which wood is one of the five elements. Indeed, the tree plays a vital role in the Korean, Chinese and Japanese cosmologies, where a tree can symbolize a link between earth (yin) and sky (yang), firmness and stability below ground and flexibility to change above ground. The white ground of the South Korean flag carries the traditional yin-yang spiral, bordered by four hexagrams taken from the I Ching. These ancient symbols represent the four seasons, the four compass points and the four elements, as well as the sun, moon, earth and universe as they rotate through an interconnected spiral of change and growth.
In the West these ideas have found new expression in the emergence sciences, which originated in the chaos theory of the mid-20th century.
The term emergence is now used to describe both the weather systems as they move across the surface of the planet and self-organization in all living systems. On a planetary scale, the term describes the dynamic force driving all biological life. Using this model as a starting point, the Santiago Theory proposes that cognition, and even consciousness, are not limited to Cartesian man but instead constitute the driving force of all biological life and an essential part of evolution itself. The Santiago Theory proposes a new way of being in the world. This shift in ontology is the first true challenge to the dualist vision of the Enlightenment period. Chaos theory and the emergence sciences that followed represent a considerable change in direction and may be the first indication that a long-overdue change in ontology is a possibility. In Tree Studies the combinations of imagery and sound can be thought of as emergent properties of the operating system’s dynamic interaction with its environment. The work has no temporal extension; like the weather, its states are never repeated and, just like the weather, it is indeed “never the same twice.”.
Each combination of image and sound is unique and exists only at the moment of its reception in the gallery space. The two interacting systems, weather and technology, operate as a continuous feedback loop, tending always toward instability and thereby generating ever new and unexpected combinations of image and sound.
Like trees in the landscape, the representation changes its form and appearance in response to input from the weather. The flickering, ephemeral nature of the projected image creates an uneasy equilibrium between the stormy winter sky, the rooted strength of the tree and the transitory nature of human presence in the landscape.
Acknowledgments
Thanks to Physicists and philosopher of science, Andrew Pickering for his excellent advice and for the pre-view of his forthcoming book on the early history of British cybernetics. Special thanks to artist/curator Mike Leggett for initiating this essay and for his tireless guidance, advice and encouragement, without which it would have remained a series of disconnected notes. Thanks to Artist/ Composer Andreas Kahre for his edit of my final draft.

References and Notes

1. Heidegger, M. “The Question Concerning Technology,” Basic Writings Ed. David Krell (New York: HarperCollins Publishers, 1993), 321.
2. Several books describe the work of the London Filmmakers Co-operative (LFMC). See also Curtis, D., ed., A History of Artists’ Film and Video in Britain (London: British Film Institute, 2006).
4. The approach taken to structural film at the LFMC can be characterized with the following quote from its main theorist: “The structuring aspects and the attempt to decipher the structure and anticipate/re-correct it, to clarify and analyze the production process of the specific image at any specific moment, are the root concern of Structural/Materialist Film.” Gidal, P., Structural Film Anthology (London: British Film Institute, 1976).
5. Hewes, G. “A History of the Study of Language Origins and the Gestural Primacy Hypothesis.” 1976 [cited 2009; Available from: <www.massey.ac.nz/~alock/hbook/hewes.htm>.
6. Maturana, H.R., “Biology of Cognition,” in Autopoiesis and Cognition (Dortrecht: D.Reidel Publishing, 1980) pp. 5–58.
7. Maturana, H.R. and F.J. Varela, The Tree of Knowledge: The Biological Roots Of Human Understanding (Boston: Shambhala, 1992) p. 245.
8. Software programming of Taking Time by Brady Marks.
9. Tree Studies was exhibited at the Gwangju Biennale in 2006. Bographical Information Chris Welsby has been making and exhibiting work since 1969. His films and film/video installations have been exhibited internationally, at major galleries such as the Tate and Hayward galleries in London, the Musée du Louvre and the Centre Georges Pompidou in Paris, the Museum of Modern Art in New York, the Carnegie Institute in Pittsburgh and the Art Gallery of Ontario in Toronto. Chris Welsby lives on Gabriola Island B.C Canada
Fig. 1. Image strips extracted from Seven Days, 16mm film, 1974. Chris Welsby)
Fig. 2. Shore Line, six-screen installation, 1977. (Chris Welsby)
Fig. 3. Changing Light, installation, Artspace, Sydney.[2004] (Chris Welsby)
Fig. 4. Time After, [Digital Media  (2010) Frame grab: refresh rate 30 minutes, Vancouver, 2010. (<c> Chris Welsby)
Fig. 5. Floor plan for Tree Studies, installation [2006] (previously Trees in Winter) (Chris Welsby)
Fig. 6. Installation of Tree Studies, Gwangju 2006 (Photo  Chris Welsby)
Fig. 7. Tree Studies, installation, [2006]. Viewed from entrance. Chris Welsby)
Fig. 8. Tree Studies, console display. (Chris Welsby)

Chris Welsby, “Technology, Nature, Software and Networks: Materializing the Post-Romantic Landscape,” Leonardo, 44:2 (April, 2011), pp. 101-106. © 2011 by the International Society for the Arts, Sciences and Technology (ISAST), published by the MIT Press. https://www.mitpressjournals.org/doi/abs/10.1162/LEON_a_00113

Leave a Reply

Your email address will not be published. Required fields are marked *