Command Types
As shown in chapter 1, "Header Types," there are three types of headers.
Each header has a corresponding command type. This section shows how
they relate to the command tree.
System Commands The system commands reside at the top level of
the command tree. These commands are always parsable if they occur at
the beginning of a program message, or are preceded by a colon. START
and STOP are examples of system commands.
Subsystem Commands Subsystem commands are grouped together
under a common node of the tree, such as the MMEMORY commands.
Common Commands Common commands are independent of the tree,
and do not affect the position of the parser within the tree. *CLS and
*RST are examples of common commands.
Tree Traversal Rules
Command headers are created by traversing down the command tree. For
each group of keywords not separated by a branch, one keyword must be
selected. As shown on the tree, branches are always preceded by colons. Do
not add spaces around the colons. The following two rules apply to traversing
the tree:
A leading colon (the first character of a header) or a <terminator> places the
parser at the root of the command tree.
Executing a subsystem command places you in that subsystem until a leading
colon or a <terminator> is found. The parser will stay at the colon above the
keyword where the last header terminated. Any command below that point
can be sent within the current program message without sending the
keywords(s) which appear above them.
Programming and Documentation Conventions
Tree Traversal Rules
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