A Help source file is a text file that consists of a sequence of topics. A topic is the fundamental unit of Help information. It is usually a screen of information about a particular subject.
Each topic begins with one or more consecutive .context statements or definitions. The topic consists of all subsequent lines up to the next .context statement. A context definition associates the topic with a “context string,” which is the word or phrase for which you want to be able to request Help. When Help is requested on a context string, the Help reader displays the topic. A context definition has the following form:
.context string
The .context command defines a context string for the topic that follows it. A context string can contain one word or several words depending on the Help reader and the delimiters it understands. For example, because Microsoft QuickBasic considers spaces to be delimiters, a context string in a QuickBasic Help file is limited to a single word. Other applications, such as PWB, can handle context strings that span several words. In either case, the application hands the context string to an internal “Help engine” that searches the database for a topic that is marked with the requested context string.
For example, the following line introduces Help for the #include directive:
.context #include
A topic can be associated with more than one context string. For example, the C-language functions strtod, strtol, _strtold, and strtoul are described in a single topic, and each is defined in a separate .context command for that topic, as follows:
.context strtod
.context _strtold
.context strtol
.context strtoul
Warning:
HELPMAKE warns you if it encounters a duplicate context definition within a given Help source file. Each context string must be unique within a database. You cannot associate a single context string with several topics in a single database.
A context string can be global or local. The string for a local context is preceded by an at sign (@). For more information, see “Local Contexts”.