PeSIT E PI codes

When implementing specific extensions, Transfer CFT uses the PI codes of the E version of PeSIT to convey specific values. These extensions are automatically activated when two partner Transfer CFTs negotiate a protocol connection in PeSIT version E. For example, requesters specify PROF = ANY in their CFTPROT object.

PeSIT E CFT/CFT extensions

PI 21 Compression

This field is used to negotiate the use of compression during the transmission of the file data. In addition to horizontal compression and vertical compression, Transfer CFT provides the possibility of using additional compression techniques:

  • compression of an EBCDIC "space" character string
  • character compacting

PI 31 Article format

This parameter specifies the file article format. It is defined using the NRECFM parameter of the CFTSEND or SEND command. In addition to the fixed format and the PeSIT variable format, Transfer CFT adds indefinite format semantics:

  • NRECFM = F     PI 31 = 0x00 (fixed)
  • NRECFM = V     PI 31 = 0x80 (variable)
  • NRECFM = U     PI 31 = 0x40 (indefinite)

PI 99 Free message

Format: 254 characters.

This parameter allows a message to be conveyed from one user to another in the free field of the PeSIT service primitives. No control concerning the coding, structure or semantics of its contents is imposed by the protocol.

This field is used to set up specific extensions by defining additional information.

The following parameters not provided for by the PeSIT protocol are conveyed:

  • NBLKSIZE, file block size (CFTSEND or SEND commands)
  • NFNAME, name of the file to be sent by the remote server (RECV command); this field is useful for reception in open mode
  • NTYPE, file type (CFTSEND or SEND commands)
  • PARM, user parameter (CFTSEND or SEND command)
  • IDT, transfer identifier of the form Mddhhmms (transfer commands HALT, KEEP, START, DELETE,...)
  • PRI, transfer priority concerning 256 possible values (CFTSEND/SEND or CFTRECV/RECV commands)
  • SYST, operating system supporting the monitor sending the FPDU
  • USERID, identifier of the user owning the file (CFTSEND or SEND commands)

This free field is also used to increase the size of certain parameters relative to the limit imposed by the PeSIT protocol:

  • Sending, or receiving, user identifier SUSER, or RUSER, limited to 8 characters by PI 03 (PI 04) can be increased to 28 characters
  • Sending, or receiving, application identifier SAPPL, RAPPL, limited to 8 characters by PI 03 (PI 04) can be increased to 48 characters
  • File identifier NIDF, limited to 14 characters by PI 12, can be increased to 28 characters

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