SPP Reference Manual
The following terms and acronyms are used in SPP, additional terms, generic to IRAF and STSDAS, are defined in the glossary in the STSDAS Users Guide.
- access mode - How to open a file or image, read-only, read-write, for example.
- argument - A value passed to a procedure. Also in the cl, a value passed to a task.
- assignment - Replace the value of a variable.
- asynchronous error - An error that results in control passing to a procedure other than the one in which the error occured.
- boolean - A binary value, yes or no, true or false.
- cell array - Grey scale image, sometimes also known as a raster or pixmap.
- clio - Interaction with the cl. The VOS library of procedures for accessing cl parameters.
- coercion - (As in type coercion.) Conversion of a value from one data type into another. Commonly by simple assignment of variables.
- comment - Text in a program file that is not executed and is retained for information purposes. In SPP, comments begin with the # character.
- common blocks - A set of ariables available to more than one procedure through common memory.
- compile - To process source code into object code, combined with other procedures to make a program (see "link").
- constant - An identifier having a fixed value.
- data structure - The organization of data in a commonly accessible form. Often includes multiple data types and arrays.
- data type - The basic attribute of a variable, constant or data value such as integer, floating point (real), double precision, boolean or complex.
- dimensionality - The number and sizes of axes of an array.
- double precision - A floating point value having more bits for the mantissa.
- error - An abnormal condition in a program
- error handler - A procedure called on an error condition to perform some activity such as closing files and cleaning up memory.
- escape sequence - Characters including metacharacters that change the interpretation of other characters. The backslash ("\") is an escape to permit specifying a character constant in SPP.
- file descriptor - A pointer to a structure describing a file.
- file name template - A file name possibly referring to more than one file, including wild-cards or a list of individual file names, or a pointer to a file containing a list of files.
- filter - A program that transforms a data set in some way without altering the fundamental structure of the data.
- fio - Basic binary file I/O not limited to images or any particular structure.
- flag - A variable indicating one of a set of possible conditions.
- floating point - A value having a decimal and fractional part.
- fmtio - Formatted I/O. The procedures for standard text and numeric I/O to files and terminals.
- function - A procedure returning a value assigned to a variable.
- gcur - Graphics cursor. Treated by the cl as a cl parameter and accessed in SPP via a clio procedure returning the coordinates of the cursor.
- generic operator - A function or operator that can be used for any of several data types.
- generic preprocessor - The program that converts generic source into compilable code specific to a given data type.
- gio - Graphics I/O. The set of VOS procedures for drawing graphs.
- graphcap - The file that describes attributes of graphics devices.
- header parameter - A value stored as part of an image file, used to describe the image.
- heap memory - Dynamically allocated memory accessed with the
malloc family of procedures.
- identifier - A string or sequence of characters having a recognized meaning such as a variable or procedure name.
- image section - (see "section.")
- imcur - Image cursor. A cl parameter type returning coordinates from an image display.
- imio - Image I/O. The library of procedures for accessing IRAF images.
- include file - Source code that can be inserted as-is into other source by referring to a file name.
- index - An integer constant or variable indicating a particular element of an array.
- integer - A constant or variable having no fractional part.
- intrinsic function - A function built in to the language. In general, the data type of the arguments and returned value may be any valid data type.
- kernel - The low-level routines implementing the system. The system procedures dealing with a particular image format. The "device drivers" for rendering graphics on a class of devices.
- keyword - An identifier or character string reserved for some purpose such as image header parameters.
- learning - The capability of the IRAF cl to remember the value of a task parameter from execution to execution.
- library - A file containing compiled procedures (object code) and linked with an application.
- link - Combine compiled code to make an executable program.
- logical task - An IRAF task implemented as part of a package or physical task.
- longword boundary - Locations in data memory separating the longest addressable units of data.
- macro - A string identified with a symbol and replaced by string substitution in code.
- mask - An image whose values indicate particular properties of another image or matching size. A mask might specify bad detector element or relative errors of pixels.
- matrix - A grouping of values in a rectangular array.
- memio - The VOS library of procedures for dynamically allocating memory.
- metacharacters - Literal characters interpreted by a parser.
- mii - Machine Independent I/O. A method of converting data that is independent of the host computer architecture. The library of procedures to perform these conversions.
- mixed mode - An expression involving variables or constants of different data types.
- mkpkg - The program that combines compiling, linking and maintaining source and objects.
- mode - Manner in which CL handles prompting and learning when dealing with parameters.
- mtio - Magnetic tape I/O.
- mwcs - Mini World Coordinate System.
- NDC - Normalized Device Coordinates. A graphics coordinate system relative to the device.
- newline - A character interpreted as a delimiter between lines of text.
- OIF - Old IRAF format. The native IRAF image format consisting of a pair of binary files, a header describing the image and a separate pixel file.
- operators - Functions combining values in an expression such as
+, -, &&.
- osb - Bit and byte operations.
- package - A library of procedures grouped by common function or a group of application tasks grouped by common function.
- parameters - The arguments to a program accessed via clio from the cl.
- pen - The logical position of drawing graphics.
- physical task - An executable IRAF program, possibly comprising multiple "logical tasks."
- plio - Pixel list I/O.
- pointer - Reference to dynamically allocated memory addresses.
- predefined constant - A program value defined at compile time, either in a
data statement or as a symbolic macro.
- preprocessor - An operation applied to program source before compilation. The generic preprocessor permits defining common code for multiple data types. xc is the preprocessor for converting SPP into Fortran.
- primitives - Relatively low-level procedures performing well-defined functions.
- procedure - The smallest executable unit of a program, called by another procedure or as a task from the cl.
- prompt - A request for input from the user via a prompt to the terminal (window).
- pset - A file containing cl parameters. A pset must be defined as a task in the cl and assigned to another task parameter. The parameter values are then available to an application as any cl parameter.
- pushback - The opposite of reading from an input stream or file. Data pushed back is then available for reading.
- QPOE - Quick Position-Oriented Event image; the native image format for the xray analysis package developed by PROS.
- Ratfor - Rational Fortran. One of the steps in converting SPP into Fortran.
- scalar - A single-valued variable.
- section - (As in "image section.") A portion of an IRAF image treated in an application as any image.
- stack memory - Dynmically allocated memory.
- STF - STSDAS format images also known as GEIS format. The native image format for HST observations. STF images are largely interchangeable with OIF images.
- stream - A source of data logically consisting of a string of characters. The standard input (STDIN), standard output (STDOUT) and standard graphics (STDGRAPH) are the most commonly used streams.
- string - Sequence of characters enclosed in quotes, for example,
"abc".
- structure - See "data structure."
- symbolic constant - A numeric value or literal string represented by an identifier. In compiled code, the value replaces the identifier by simple string substitution.
- task - A program known to IRAF, a command in the cl.
- templates - See "file name templates."
- termcap - The IRAF file that describes attributes of text terminals.
- token - The smallest sequence of characters recognized by a parser, a number or identifier, for example.
- tty - Terminal I/O.
- unary operator - An operator requiring only one operand, such as negation.
- vector - An array, a contiguous group of values accessed through a common variable name.
- vops - Vector operators. The library of procedures that operate on arrays, potentially optimized for the host architecture.
- VOS - Virtual operating system. The set of procedures called by an applications tasks for performing IRAF functions.
- WCS - World Coordinate System. Coordinates associated with data rather than a device or an arbitrary scale.
- white space - Any number of tabs, spaces or newline characters separating entities in a string.
- word - The fundamental unit of accessing data in a program, usually several bytes long. The word size varies between host architectures.
- xc - The program that compiles and links SPP, Fortran, and C code to produce an executable, or physical task.
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