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

Appendix K 637
SNA DHCF with VPLUS Applications
IBM 3270 Differences and Limitations
• Character translation
Screen Attributes
IBM 3270 display stations have the following screen attributes and limitations:
Display Area Depending on the IBM 3270 display station model, the
display area is either 24, 32, or 43 lines long. The
maximum length for a VPLUS form is 24 lines.
Consequently, if you display a VPLUS form on an IBM
3270 that has 32 or 43 lines, the lines following line 24 will
be blank.
SNA DHCF reserves the last two lines of the display area
for function key labels. Therefore, a form can consist of
either 21 lines including a window line, or 22 lines without
the window line.
Status Line A status line appears below the display area. SNA DHCF
applications, including VPLUS, cannot access the status
line. Only the display controller can update this line.
Window Line A window line defined in a forms file consumes a line of
the available display. If you define a window line in the
forms file, you must place the window line on line 1 or line
22, because IBM 3270 limitations prohibit inserting a line
in the middle of a form. Selecting a window line reduces
the form length to 21 lines.
You must reserve a fixed line if you define a window line in
a forms file, because window lines cannot be inserted.
SNA DHCF limits the text in a window line to 79 bytes
instead of 80, because space must be reserved for the
attribute byte. Text exceeding 79 bytes becomes truncated.
(Refer to the sectionentitled "Fields" for information about
the attribute byte.)
Modified Data Tag An IBM 3270 functions as a modified data tag (MDT)
device. It transmits to the HP 3000 only the data that the
end user has modified.
Limitations The following IBM 3270 limitations are important to note
when designing or modifying VPLUS applications. The
IBM 3270 does not have:
• Forms caching capability
• Terminal memory other than display memory, which
consists of a 24-line length and 80-column width
• Scrolling capability
In addition, the IBM 3270 does not support:
• The line-drawing character set provided on some HP