HP Data Entry and Forms Management System (VPLUS) Reference Manual (32209-90024)

Chapter 6 253
USING VPLUS INTRINSICS
USING TERMINAL FEATURES
Appending Forms and Local Storage
The implementation of appending forms differs between the HP 2626A and the HP
2624B/HP 2394A terminals. On the HP 2626A, the appending form is always written to
the screen from the form definition area of memory rather than being displayed from local
storage. If, however, the appending form has 24 or more lines (23 or more if a message
window is defined), it is handled as an independent form rather than as an appending one.
In this case, it can be displayed from local storage.
The workspace for the current form (the one being appended to) is marked available, so the
current form cannot be displayed again from local storage.
Form family optimization occurs when the current form is an appended form and is related
to the next form to be displayed. The current appended form is changed into the required
form when it is displayed.
On the HP 2624B/HP 2394A terminals, the appending form can be copied from local
storage.
Purging Forms From Local Storage
The VUNLOADFORM intrinsic is used to purge an unneeded form from local storage to make
room for a new form. This intrinsic checks to see whether or not a form is purged. During
this cheek, the keyboard is locked briefly. To avoid possible loss of keystrokes and/or
entered data, do not call VUNLOADFORM between VSHOWFORM and VREADFIELDS. In addition,
the intrinsics VCLOSEFORMF and VCLOSETERM also clear all forms from local storage.
With look-ahead loading, forms can be automatically purged from the terminal to make
room for a new form. To protect forms from being purged from local storage, set
lookahead
to one before any other calls to VREADFIELDS or to VLOADFORMS. If lookahead is zero, the
least recently used forms are purged if necessary. However, when
showcontrol bit 9 is set
to one, forms can be purged to make room even if look-ahead is not enabled.