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File Lines and Command Blocks

The input data is a collection of file lines. Upto 80 characters in a line is read in. (This limitation can be easily changed by modifying the parameter statement in the main program.)

If a character ``!'' is encountered, the whole text after it to the end of the file line is considered as a comment , unless the ``!'' is in a pair of apostrophes. apostrophe pairs must close within a line except for comment parts. Apart from the above two points, the concept of `file line' is irrelevant. Therefore, for example, continuing the two file lines will give the same results, and the end of a command must explicitly said (by semicolon ``;'') without relying on the end-of-line.

The whole text, after comment part is eliminated, is divided into `command blocks'. The end of a command block is indicated by a semicolon ``;''. If ``;'' is inside a pair of apostrophes, it is not considered to be a command terminator .

Each command block has the following structure:

20mm command_name operand, operand, tex2html_wrap_inline7216 operand ;

After the command_name before the first operand, there must be at least one blanck character (unless there is no operand). Operands are separated by a comma ``,'' and the number of blancks before and after ``,'' is arbitrary. (In some commands, ``,'' can be replaced by one or more blancks). Unless stated in each command description in the next section, the order of operands is arbitrary.

An operand is either a single keyword or of the form

20mm keyword relational_operator right_hand_side

A keyword is an alphanumerical string predefined for each command. The relational operator  is either one of =, &#;'74, &#;'76, &#;'74=, &#;'76=, =&#;'74, =&#;'76, &#;'74, &#;'76. The right_hand_side is just a number or an `expression' (to be explained later) or of the form

20mm ( expression, expression, tex2html_wrap_inline7216 expression)

The parenthesis ( ) may be replaced by [ ] or &#;'173 &#;'175.

next up previous contents index
Next: Commands Up: Basic Grammer of the Previous: Characters

Toshiaki Tauchi
Thu Dec 3 17:27:26 JST 1998