.LP
Control structures are used to create more complex visual
programs by providing looping and decision constructs.
.SH
OVERVIEW
.LP
A specific programming \fIcontrol structure\fP is selected by clicking on
the appropriate button from the "guide pane" on the left of the subform.
Once the desired structure has been selected, a pane will appear
on the right of the subform with parameter values which may then be
modified.  Additional documentation for each control structure is
available under `Help' on the pane for that structure.
.PP
All control glyphs have an extra button at the top of the glyph.
This `RESET' button is used to set the glyph so that when next run, the 
initial input to the glyph will be accepted and the initialization
steps re-executed.
.PP
Glyph connection names for control glyphs represent "flow of
control" as well as "flow of data".   The flow of data is explicitly
determined by the connections made, but the flow of control is
implied by your program structure.  As an example, the Count-Loop
discussed later can accept a feedback path from anywhere in the
sequence of glyphs that are connected to its output, but the entire sequence
is assumed to be part of the loop.  (See examples of no feedback vs. with
feedback).
.SH
SHORT DESCRIPTIONS
.IP "Count-Loop" 15
Used to create a counting loop similar to a \fIfor\fP or \fIDO\fP loop..
.IP "While-Loop" 15
Used to create a conditional loop.
.IP "If-Then-Else" 15
Used to create a decision structure or program branching.
.IP "Merge" 15
Used to merge two data paths together (as at the end of an
If-Then-Else).
