Envoy Application Programming Manual

Burroughs Point-To-Point Protocol
Envoy Application Programming Manual—427159-001
9-6
Normal Text
Messages must be formatted according to protocol rules. Prior to transmitting a
message, the specific control characters for a particular message type (such as heading,
text, or transparent text) must be placed in the message by the application process. When
a message is received, the control characters are returned in the data to indicate the type
of message received. Note that a message, as received in the application’s buffer, does
not contain control-generated sync characters, inserted DLE characters (for transparent
text), or block-check characters.
The following types of message formats are allowed:
•
Normal Text on page 9-6
•
Headings on page 9-6
Normal Text
Normal text is indicated by messages having the following form:
message = STX—text—ETX
message = DLE—bl#—STX—text—ETB
message = DLE—bl#—STX—text—ETX
Headings
Table 9-4 lists the formats used for headings.
The block number (bl#) is modulo 7, represented by the lowercase letters listed in
Table 9-5
.
Table 9-4. Format for Headings
Heading Format
Heading only DLE-bl#-SOH-heading-ETB
Heading and normal text SOH-heading-STX-text-ETX
DLE-bl#-SOH-heading-STX-text-ETB
DLE-bl#-SOH-heading-STX-text-ETX
Table 9-5. Lowercase Letters for Block Number
Block Number bl#
0p
1q
2r
3s
4t