1  –  BLOCK count

 Applies only to X25 lines. Specifies the maximum size in bytes of the
 frame for the line. This value must be at least 5 bytes larger than
 the maximum packet size you specify in  SET CIRCUIT (for PVCs and
 DLM circuits) or SET MODULE X25-PROTOCOL (for SVCs). Specify a value
 in the range 21 to 4103.

 By default the size of the frame takes the value specified by the
 PROFILE parameter of the SET MODULE X25-PROTOCOL command.

2  –  RETRANSMITS count

 Applies only to X25 lines.  Specifies the maximum number of
 retransmissions of a frame on the specified line. Specify a value in
 the range 1 to 255.  By default, the retransmission value takes the
 network value specified by the NETWORK parameter of the SET MODULE
 X25-PROTOCOL command.

3  –  WINDOW count

 Applies only to X25 lines. Specifies the maximum
 window size allowed for the X25 circuit - that is, the maximum number
 of packets for which outstanding acknowledgments are allowed. Specify
 a value in the range 1 to 127.

 By default window size takes the value specified by the PROFILE
 parameter of the SET or DEFINE MODULE X25-PROTOCOL command.