NET/MASTER Network Control Language (NCL) Programmer's Guide

Defining Field Characters in a Panel Description File
Working With Panels
14–48 106160 Tandem Computers Incorporated
During this preliminary phase, field characters are ignored and substitution is used to
change a panel line in any way you require. When preparsing is complete, the normal
panel building process is performed.
Substitution uses the occurrence of the ampersand (&) to indicate the start of a variable
string. These strings can be resolved to reflect the content of the variable, as set by an
NCL process before it executes the PANEL verb.
Preparsing is regarded as a completely separate substitution phase. Therefore, if a
preparse character other than an ampersand (&) is designated, this process can
substitute data that includes other variables that are resolved when the standard
substitution process for each field is performed. There are two types of preparsing:
dynamic preparsing and static preparsing.
Note You can also preparse panel control statements, since preparsing takes effect immediately after the
#OPT PREPARSE panel control statement.
Dynamic Preparsing
Dynamic preparsing moves fields (the beginning is marked by the position of a field
character). It allows preparse or field characters to move to accommodate differing
substituted data lengths.
In panel lines with more than one preparse character or field character, the effect of
substituting variable data within the line may cause the final text of the line to be
longer or shorter than the original text. In this case, fields that follow the substituted
data move to the left or right of their original columns.
Static Preparsing
Static preparsing preserves field positions (the beginning is marked by the position of
a field character). It does not allow preparse or field characters to move to
accommodate differing substituted data lengths.
If you are displaying a panel where column alignment is important for the
presentation, but you are using preparse to substitute data into each line, you may find
the columns are not aligned properly in the final display. This occurs because the
substituted data varies in length from line to line.
To correct this, use static preparsing. This lets you specify in the #OPT statement that
the location of preparse and field characters is to be preserved, despite different data
substitution lengths. Here, data is truncated to fit if the substituted data exceeds the
space available to the left of the next preparse or field character.