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8.5 How a Command Line is Processed

When FunnelWeb reads in a command line (from the console or a script file), it processes it in the following sequence:

1. The command line is checked for non-printable characters. If there are any, they are flagged with a severe error.
2. All dollar string substitution variables in the command line are replaced by their corresponding string. The command line is processed from left to right. Substitutions are performed non recursively.
3. At this point, if the line is empty, or consists entirely of blanks, it is ignored and the interpreter moves to the next line.
4. A severe error is generated if the line at this stage begins with a blank.
5. If the first character of the line is "`!`", the line is a comment line and is ignored.
6. The run of non-blanks commencing at the start of the line is compared case-insensitively to each of the legal command verbs. If the command is illegal, a severe error is generated, otherwise the command is processed.

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