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

Appendix K 639
SNA DHCF with VPLUS Applications
IBM 3270 Differences and Limitations
Fields
You should not design a form that has contiguous fields, because the IBM 3270 display
station requires an attribute byte preceding each field or text area. The attribute byte uses
a physical screen location and appears as a blank space on the screen. The attribute byte
indicates whether the field can be or has been changed.
You can create a space for both leading and trailing attribute bytes by inserting visible
brackets before and after all fields. SNA DHCF can convert these visible brackets to
invisible attribute bytes on IBM 3270s. For instance, if you defined the following three
fields:
[08][05][52]
they would appear as shown below when the VPLUS form is displayed on an IBM 3270
screen.
*08**05**52*
The * represents an attribute byte. On the screen, the attribute byte appears as a blank.
If you use invisible brackets to delimit fields, you must provide a leading space before each
field or text area. When the field or text begins in the first column of a line, insert the space
at the end of the previous line. The "Home" position is an exception to this guideline; the
attribute byte should be inserted in the bottom right position instead (reverse "Home").
Although the attribute byte is the most important concept regarding fields for IBM 3270
display stations, you should also be aware of the following information about fields.
Character Translation
As mentioned earlier, HP computer systems use ASCII character sets, whereas IBM
computer systems use EBCDIC character sets. Consequently, SNA DHCF must use system
default translation tables from the Native Language Subsystem (NLS) to translate
characters from one system to the other.
If Native-3000 is the native language used, SNA DHCF translates all ASCII characters
without alterations, except for the characters shown in table K-4. Note that the HP
terminal bracket characters equate to text, not actual FORMSPEC brackets.
To display one of these characters on one system, you must specify the corresponding
character on the other system. For instance, if you want to send an exclamation point (!) to
an IBM 3270 user, your VPLUS application must specify this character as a right bracket
(). If an IBM user wants to input a left bracket (), he or she must specify ¢.
Table K-4. Differences Between HP and IBM Character Displays
HP Terminal Character ASCII Hex Value IBM 3270 Character EBCDIC Hex Value
[5B¢4A
]5D!5A
!21 4F
^5E 5F