HELP

Presents online help information.

Syntax

HELP [topic]

Parameters

For files that invoke the winhelp executable

topic

A character string or a number, or an expression that evaluates to a character string or a number. Identifies a particular help topic in the help file.
If topic is a character string, the HELP command accesses the help file with topic as a keyword. If topic contains the pattern-matching wildcard character "%", HELP uses the prefix of topic, up to the first "%" as the keyword. A partial key match is done, and matching keywords are displayed in a search window.
If topic is a number, it is assumed to represent a "context ID". HELP accesses the help file using topic as the "context ID".
If the keyword or "context ID" provided by topic is invalid, a warning message is displayed, followed by the help topic search window.
If topic is blank or $Null, HELP shows the first topic in the help file.

Note: For Explorer-style hypertext Help files, topic is a character string or a number, or an expression that evaluates to a character string or a number which identifies a particular help topic in the help file. It invokes the name of one of the .html files that were used to build the . chm file.

Comments

The HELP command displays online help about a given topic. By default, the command accesses the help file, ZDL.CHM, in the directory containing the software. To use another help file, set the system variable $ HelpFile to the name of the desired help file.

In the Windows environment, the HELP command determines, based on the extension of the help file, whether to invoke the Internet Explorer's hypertext help viewer ( hh.exe) or to invoke the Windows help driver ( winhelp.exe) to display the help topics.

Winhelp help files

If the help topic is specified as a character string, the HELP command passes the string to the help driver as a keyword. If an exact match is not found, the help driver displays a warning message, following the topic search window.

If the character string contains the pattern-matching wildcard character $, HELP passes the string to the help driver, up to the first $ character, as a keyword prefix. Keywords that match the prefix are displayed in a topic search window for selection.

If the help topic is specified as a number (any numeric data type), HELP passes the number to the help driver as a topic identifier. If the identifier is invalid, the help driver displays a warning message, followed by the topic search window.

If no help file can be found, the software raises an error.

Hypertext help files

The hypertext help viewer accepts only strings as topic names and they must match the html files that were used to build the . chm file.

 

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