Glossary
Alphabetical definitions of SELES-specific terms, file types, and concepts used throughout this documentation. For named expression functions (e.g. ABS, REGION RECT), see the Expression Quick Reference instead.
| Term | Definition | See also |
|---|---|---|
| Absolute Probability | When NumClusters/NumRecipients is not defined, ProbInit/SpreadProb is treated as an absolute probability (normally 0–1) that the event initiates or spreads in a given cell, tested independently per cell. | Landscape Events |
| Accumulate | A keyword placed after a global or spatial variable definition in a .sel file specifying that the variable is initialised only at the start of the first run of a multi-replicate simulation and accumulates across runs instead of resetting. | .sel Reference |
| Active Cell | A cell currently being processed by a landscape event — either just initiated or on the active spreading front; it remains active until it fails Transitions or finishes spreading. | Landscape Events |
| Active Cell Context | The spatio-temporal context of a single active cell, where cell, cluster, event, and layer values at that cell are all available. | State Space |
| Active Recipient Context | The context created for a neighbouring cell once it has been selected (via NumRecipients) to receive spread, giving it its own active-cell variables alongside the source cell's SOURCE-prefixed values. | State Space |
| Align Layer | A Static Models tool that reprojects/clips the selected raster view to match another layer's georeferencing (rows, columns, extent), producing a new view prefixed aligned_. | Interface |
| Cell Variable | A dynamic context variable unique to each active cell in a cluster (e.g. fire Intensity); created when the cell activates and removed when it terminates. | Landscape Events |
| Cluster | The set of active cells sharing a common initiation cell; stays active while it has at least one active cell, terminating (EndCluster) when none remain. | Landscape Events |
| Cluster Variable | A dynamic context variable unique to each active cluster within an instance (e.g. FireSize, the target size of one fire patch). | Landscape Events |
| Configuration Expression | A restricted expression form used in .sel files, limited to arithmetic combinations of numbers and previously-defined constants/variables (no stochastic or spatial functions). | .sel Reference |
| Consequent Context | The new context(s) created as a result of evaluating a landscape event property — e.g. specifying 3 ignitions creates 3 new active-cell contexts. | State Space |
| Consequent Expression | The expression(s) evaluated after a property's main expression, in the context that property's evaluation creates (e.g. state changes once Transitions passes). | .lse Reference |
| Context (Spatio-temporal Context) | The set of state variables available at a particular simulated time and grid cell; contexts progress from Global → Event Instance → Spatial → Active Cell → Recipient → Active Recipient. | State Space |
| Definitions Section | The DEFINITIONS…ENDDEF block of a .lse or .ce file that declares which shared state-space variables (layers, global constants/variables, macros) and event-local variables the file uses. | .lse Reference |
| Discrete Event Simulation (Engine) | The SELES engine that maintains a priority queue of scheduled events in chronological order, always processing the event(s) at the head of the queue before advancing simulated time in discrete steps. | Overview |
| Dry Run | An option that opens and processes a scenario file, performing all tasks except actually running the simulation, so its syntax can be checked. | Interface |
| Dynamic Model File (.sel) | The file defining a model's spatio-temporal state space (spatial/global constants and variables, time units, legends, macros) plus the landscape event files it uses. | .sel Reference |
| End Cluster (EndCluster) | The property processed when a cluster terminates (no active cells remain); in SELES 10 only its preliminary context is defined, so it is mainly used for cleanup. | Landscape Events |
| End Event (EndEvent) | The property processed when an event instance terminates (no active clusters remain); like EndCluster, only its preliminary context is currently defined. | Landscape Events |
| Event Instance | A single dynamically-created, scheduled occurrence of a landscape event's definition, as distinct from the static definition in the .lse file. | Landscape Events |
| Event Instance Context | The non-spatial context of an active event instance before it has initiated in any cells — used by ReturnTime and EventLocation. | State Space |
| Event Location (EventLocation) | The property defining the set of cells (a region) in which an event can potentially initiate; default is the whole map. | Landscape Events |
| Event Queue | The simulation engine's priority queue ("Q") of scheduled events, always ordered so the next event to process sits at the head. | Overview |
| Event Variable | A dynamic context variable unique to each active event instance (e.g. NumFires, a per-storm-instance count). | Landscape Events |
| External Variable | A script variable defined in a scenario (.scn) file and imported into a .sel file, substituted literally wherever referenced — commonly used to parameterise file paths and names. | .sel Reference |
| Fixed-Point Value | A way of representing decimal numbers in an integer-valued raster by storing values multiplied by a chosen precision factor (e.g. storing 12.34 as 1234 with factor 100). | Input Data |
| Global Constant | A static, named, non-spatial value that cannot be modified during a simulation; improves readability and centralises values that may change between scenarios. | .sel Reference |
| Global Context | The context at simulation start-up, before any process begins — no spatial location and no active event instance yet. | State Space |
| Global Variable | A non-spatial state variable that may change over time (but not space), such as wind direction; can serve as a model parameter, output statistic, or channel between landscape events. | State Space |
| Grain and Extent | The requirement that all rasters in a model share the same cell size ("grain") and number of rows/columns ("extent"); SELES offers limited rescale/align tools but the correct scale is the modeller's responsibility. | Overview |
| Immediate Mode | A SpreadTime behaviour triggered by a negative value, in which spreading bypasses the main event queue and is processed immediately via a temporary per-cluster queue, so a patch can finish spreading before the next cluster initiates. | .lse Reference |
| Initial State | The set of landscape conditions (spatial and non-spatial) before a simulation begins; also the property name for how many event instances are created at start-up. | Overview |
| Initiation vs. Occurrence | SELES's distinction between an event instance being "dropped" into a cell (initiation, via EventLocation/NumClusters/ProbInit) and the event actually taking effect there (occurrence, via the Transitions test). | Landscape Events |
| Landscape Event | The primary SELES modelling abstraction: a semi-independent sub-model representing one process of landscape change that recurrently initiates, may spread across cells, and changes state; events interact only through shared state, never directly. | Landscape Events |
| Landscape Event File (.lse) | The file defining a single landscape event's variable declarations and properties (when, where, and how it initiates, spreads, and changes state). | .lse Reference |
| LHS / RHS | Shorthand used in the Model Report for whether a variable is modified ("left-hand side" of an assignment) or only read ("right-hand side") within each landscape event that references it. | Interface |
| Legend | A set of named constants tied to raster cell values (e.g. 1 = Conifer), loaded in a .sel file as global constants; improves readability and model portability versus raw numbers. | Input Data |
| Local Variable | A non-spatial variable that is global in scope but private to a single landscape event, not part of the shared state space; declared LOCAL, undefined until first assigned. | Landscape Events |
| LSEditor | A dedicated text editor for SELES files (.scn, .sel, .lse) offering syntax colouring and an embedded copy of the SELES parser, so syntax and state-space consistency can be checked without opening the full application. | LSEditor |
| Macro (.ce File) | A named array of function expressions, defined in a .ce file and loaded via a .sel file's MACROS block; indexing a macro evaluates its function at that index in the current context, rather than returning a stored value like an ordinary array. | .ce Reference |
| Model Dimensions | A scenario command that sets the scenario's working rows/columns to match a loaded raster view; must precede loading the dynamic model file. | .scn Reference |
| Model Report | A generated report (SelesModelReport.txt) listing every variable/constant, the landscape events referencing it, and whether it is modified (LHS) or only read (RHS) — used to verify model structure. | Interface |
| Monte Carlo Run | One of possibly many stochastic replicate simulations of the same model, needed because a single stochastic run represents only one possible sequence of change. | Overview |
| Number of Clusters (NumClusters) | The property specifying how many cells (clusters) an event should initiate in, used together with ProbInit. | Landscape Events |
| Number of Recipients (NumRecipients) | The property specifying how many neighbouring cells an active cell should spread to, used together with SpreadProb. | Landscape Events |
| Operating Context | The context in which a property's preliminary and main expressions are evaluated, reflecting the event's state up to that point. | Landscape Events |
| Output Variable | A landscape-event variable (declared OUTPUT VARIABLE) used to write records to a tab-delimited output file rather than hold ordinary state. | .lse Reference |
| Parameter | Broadly, any input that sets a model's initial conditions; most often refers to state-space elements deliberately designed to be changed between scenarios. | State Space |
| Parse / Parsing | Checking a model file's syntax (and, for .lse files, state-space consistency) without running a full simulation, via LSEditor's Parse (Check…) or Parse and Save. | LSEditor |
| Preliminary Expression | The expression(s) in a property evaluated before its main expression, in that property's operating context. | .lse Reference |
| Probability of Initiation (ProbInit) | The property giving the absolute or relative probability that an event initiates in a given cell, evaluated over the EventLocation region. | Landscape Events |
| Probability of Spread (SpreadProb) | The property giving the absolute or relative probability that an active cell spreads to a given neighbour, evaluated over the SpreadLocation region. | Landscape Events |
| Raster | A rectangular grid of fixed-size cells, each holding a single numeric value; SELES's primary form of spatial input/output data. | Input Data |
| Raster Vector | A spatial constant/variable defined as an ordered list of raster views rather than a single raster, forming a multi-layer array. | .sel Reference |
| Raster View | A named, in-memory window onto a raster grid within SELES, created when a raster is opened or a new layer made, and referenced by name in scenarios and .sel files. | Interface |
| Recipient Context | The context of a candidate neighbouring cell during spreading, after SpreadLocation has identified it as a potential recipient but before it is actually selected. | State Space |
| RECOMPUTE | A flag on ProbInit/SpreadProb (paired with a RECOMPUTE expression, typically in Transitions) that forces the probability surface to be re-computed during initiation/spreading rather than only once at the start. | .lse Reference |
| Region (Region Function) | An expression returning a set of cells; the only expression type usable as the main expression of EventLocation or SpreadLocation. | .lse Reference |
| Relative Probability | The interpretation of ProbInit/SpreadProb values when NumClusters/NumRecipients is defined: values act as selection weights for a fixed number of cells rather than independent absolute probabilities. | Landscape Events |
| Rescale Layer | A Static Models tool that changes a raster's cell size, aggregating old cells into new ones (mode, mean, minimum, etc.) when increasing cell size, or subdividing when decreasing it. | Interface |
| Resize Layer | A Static Models tool that changes a raster's number of rows/columns without changing cell resolution, based on specified bounds. | Interface |
| Return Time (ReturnTime) | The property defining the time interval between the creation of one event instance and the next — how often the event recurs. | Landscape Events |
| Scenario Script (.scn) | A file of commands, executed in order, that loads rasters and model files, sets parameters, and runs simulations. | .scn Reference |
| Script Variable | A text-substitution variable, delimited by $…$, defined and used in a scenario script (and optionally imported into a .sel file) to parameterise file names, paths, and iterative runs. | .scn Reference |
| Selection Box | A rectangular area set with the mouse on a raster view, used as the default region for value-summary models and raster resizing. | Mouse & Keyboard Controls |
| Selection Order Flags (RANDOM, ORDERED, WITH REPLACEMENT) | Optional flags on NumClusters, ProbInit, NumRecipients, or SpreadProb that change candidate-cell selection: RANDOM shuffles processing order, ORDERED processes by decreasing probability value, and WITH REPLACEMENT allows a cell to be selected more than once. | .lse Reference |
| SimStart | The scenario command that starts a simulation for a given run length (and optionally a number of Monte Carlo runs), after a dynamic model has been loaded. | .scn Reference |
| SOURCE Keyword | In spreading contexts, a prefix referring to layer and cell variable values at the source spreading cell rather than the current (recipient) cell. | .lse Reference |
| Spatial Constant | A state variable that varies over space but not over time (e.g. elevation), with no separate initial-conditions raster distinct from its current value. | State Space |
| Spatial Context | The context in which a set of cells has been identified as initiation candidates (via EventLocation) but not yet activated. | State Space |
| Spatial Variable | A state variable that varies over both space and time (e.g. stand age), changed by landscape events during a simulation. | State Space |
| Spatio-temporal State Space (State Space) | The complete set of spatial and non-spatial variables/constants, plus a time unit, that defines a model's state at any point in a simulation. | State Space |
| Spread Location (SpreadLocation) | The property defining the set of cells to which an active cell can potentially spread; default is the four cardinal neighbours. | Landscape Events |
| Spread Time (SpreadTime) | The property defining the time interval between an event occurring in a cell and its spreading to neighbours; a negative value triggers Immediate Mode. | Landscape Events |
| Static Model | A model type (Neutral, Fractal, Site, or Value Model) that produces a single output — a raster view or a value — rather than dynamics over simulated time. | Interface |
| Stochastic Model | A model whose behaviour includes random elements, ranging from nearly random to nearly deterministic; typically requires multiple Monte Carlo runs since one run is only one possible outcome. | Overview |
| Submodel | A subordinate .sel file loaded into a parent .sel file, whose state space becomes part of the main model; omits the SELES MODEL declaration and time units block. | .sel Reference |
| System Constant | One of a fixed set of always-available constants (NUMROWS, NUMCOLS, NUMCELLS) describing the scenario's raster dimensions. | .lse Reference |
| System Variable | One of a fixed set of always-available variables (Time, EndTime, Run, Location, Index, EventId) providing built-in simulation state without needing to be declared. | .lse Reference |
| Temporary Local Variable | A variable used in a landscape event that is neither declared nor a system variable; created automatically on first assignment and scoped only to the immediately following expressions of that property. | .lse Reference |
| Time Unit | The named base unit (and meta-unit) of simulated time defined in a .sel file's TIME UNITS block (e.g. base Year, meta-unit Century = 100 years), used for display and default simulation length. | .sel Reference |
| Transitions | The property that tests, in an active cell, whether the event actually "occurs"; if true, main state changes happen and spreading is attempted, otherwise the active cell terminates. | Landscape Events |
| Undefined Cell | A raster cell value (often a sentinel like −1) marking areas outside the study area or with no data; SELES makes no assumption about it, so events must be written to avoid operating there. | Overview |
| Value Model | A static model producing a single summary value (mean, sum, max, etc.) from a cell expression over a region; can also bulk-edit raster cell values. | Interface |
| Variable Scope | The rule determining where a variable is valid and what context it belongs to — e.g. global (single aspatial value) vs. spatial (per-cell value in spatial contexts) — applied to every SELES variable type. | .lse Reference |