Previous: debug-file Up: ../slides.html Next: delete
The DEFINE command may be used to define a text character assignment, or to define scalar and/or vector variables within the expression parsing system. In the first case, 'character' represents the symbol numbered HersheyIdNumber in the font library. When that character appears in a string drawn by the TEXT command, the specified symbol will be drawn instead of the usual symbol attached to that character. The redefinition of the character applies only to the current font. This may be used to access Hershey characters which are not attached to any characters in the selected fonts. The later sections ALPHABETICAL-CHARACTER-INDEX and NUMERICAL-CHARACTER-INDEX provide cross-references of the Hershey special characters. When a parenthesized expression follows the DEFINE command, it is collected and passed directly to the expression parser for evaluation. Any numerical values returned for it are simply ignored. Since the expression parser is quite powerful and supports a symbol table, the expressions may assign scalar or vector values to variables which may subsequently be used throughout SLIDES wherever a parenthesized expression is permitted, which is anywhere a numerical value is expected.