The Message Switching Control Block (MESGCB) is a working storage area in the application program containing the information Com-plete needs to control the processing of the MESGSW switching function. The format and content of the MESGCB follow:

Location		Length	Format	Contents
Dec	Hex
0	0	1	Character	L (=Last segment) space
	1	1	Character	Reserved. Must be initialized to a space.
	2	2	Binary	Message identification number. Must be initialized to spaces. Com-plete inserts the message number assigned to the message when the first segment is sent.
	4	2	Binary	Class codes. See the following table.

The class codes specified in the MESGCB are defined as bit settings in the halfword located at relative offset four. The following table details the bit settings associated with specific class codes:

 

BIT POSITIONS

Class Code	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
1	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	1
2	.	.	.	.	.	.	.	.	.	.	.	.	.	.	1	.
3	.	.	.	.	.	.	.	.	.	.	.	.	.	1	.	.
4	.	.	.	.	.	.	.	.	.	.	.	.	1	.	.	.
5	.	.	.	.	.	.	.	.	.	.	.	1	.	.	.	.
6	.	.	.	.	.	.	.	.	.	.	1	.	.	.	.	.
7	.	.	.	.	.	.	.	.	.	1	.	.	.	.	.	.
8	.	.	.	.	.	.	.	.	1	.	.	.	.	.	.	.
9	.	.	.	.	.	.	.	1	.	.	.	.	.	.	.	.
10	.	.	.	.	.	.	1	.	.	.	.	.	.	.	.	.
11	.	.	.	.	.	1	.	.	.	.	.	.	.	.	.	.
12	.	.	.	.	1	.	.	.	.	.	.	.	.	.	.	.
13	.	.	.	1	.	.	.	.	.	.	.	.	.	.	.	.
14	.	.	1	.	.	.	.	.	.	.	.	.	.	.	.	.
15	.	1	.	.	.	.	.	.	.	.	.	.	.	.	.	.
16	1	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.

Copy code for the MESGCB is provided in the Com-plete source library: COBMSCB for COBOL, and PL1MSCB for PL/I.