HELPMAKE creates a Help file by encoding a source file. A Help file contains information that can be read by a Help reader (sometimes referred to in this chapter as an application). Examples of Help readers are the Microsoft Advisor or Microsoft QuickHelp. Help files have an .HLP extension.
Source files for HELPMAKE are text files that contain topic text along with attributes and commands that tell HELPMAKE how to process the file. HELPMAKE encodes text files written in the following formats: QuickHelp, rich text format (RTF), and minimally formatted ASCII.
Encoding compresses the text and translates the commands into information for the Help reader. You can control the amount of compression and other aspects of encoding.
HELPMAKE can also decode an existing Help file. Decoding decompresses the text into ASCII format. Attributes and commands can be preserved or omitted during decoding. You can modify an existing Help file by using HELPMAKE to decode the file and then rebuild it into a different Help file. You can even modify a Microsoft help file by decompressing it and then encoding it with your changes. Regardless of the source format, HELPMAKE always decodes a Help file into the QuickHelp format.
The basic unit of Help is the database. A Help database is an individual file created by HELPMAKE. At the time it is created, it is given an internal name that is the same as the filename on disk. If the file is later renamed, the database retains this internal name as it is known by HELPMAKE and the Help reader.
A Help system consists of one or more physical Help files that are available to a Help reader. A physical Help file is a file on disk with an .HLP extension. It can contain a single database (with either the same or a different filename) or multiple databases. To create a physical Help file that contains several Help databases, use the DOS COPY command. Specify the /b modifier to combine them as binary files. You can merge several databases into one physical Help file, combine two or more physical Help files, or append a Help database to an existing physical Help file. For example, the following command concatenates three individual Help databases into a new physical Help file:
COPY help1.hlp /b + help2.hlp /b + help3.hlp /b myhelp.hlp
The next example merges the database yourhelp.hlp with the existing Help file utils.hlp:
COPY utils.hlp /b + yourhelp.hlp /b
It is recommended that you back up existing Help files before running the COPY command. You may need to concatenate Help files if you reach a limit on physical files imposed by your system or the Help reader.
You can use HELPMAKE to deconcatenate, or split, a physical Help file that contains multiple databases. If you want to decompress such a Help file, you must first split it and then decompress each database.
When designing a Help system, it is important to know that a single database is more efficient to search than multiple databases or physical Help files.