Use of the Character “c” for the NI, NC, NCM, ZONE, AREA, ID, NPC, MSA, SSA, and SP Parameters

The character “c” is used in the blocked OPC or DPC screens (for parameters ni, nc, ncm, zone, area, id, npc, msa, ssa, and sp) to allow the screening process to continue for messages with point codes that do not match any point codes in the blocked OPC or DPC screens. The character “c” is used this way. When screening for a blocked OPC or DPC and the point code being screened does not match any of the point codes in the blocked OPC or DPC screens, the message is not rejected and the screening process continues. To allow the screening process to continue, the blocked OPC and blocked DPC screens must have at least one entry consisting of a screening reference, a point code, a next screening function identifier, and a next screening reference. The point code is in the form of ni=c, nc=c, ncm=c (for ANSI point codes), zone=c, area=c, id=c (for ITU international point codes), npc=c (for 14-bit ITU national point codes), and msa=c, ssa=c, sp=c (for 24-bit ITU national point codes). When the character “c” is specified, the next screening function identifier and next screening reference must be specified, unless the next screening function identifier is stop (nsfi=stop). Then the next screening reference cannot be specified.

When the point code does not match any entries in the blocked OPC or DPC screens, the screening process is directed to the screening reference with the point code c-c-c or npc=c. The next screening function identifier and next screening reference in this entry are examined to determine the next step in the screening process.

When a blocked OPC or DPC screen is created, the first entry for the ni-nc-ncm, zone-area-id, or msa-ssa-sp must be c-c-c, or the npc must “c.” Subsequent entries can be specific point codes.

If the character “c” is specified for any parameters ni, nc, ncm, zone, area, id, msa, ssa, or sp, it must be specified for all three parameters. No other values can be used. For example, a point code c-c-255 is not allowed. The point code must be c-c-c. The “*” (asterisk) value cannot be used with the character “c” (for example, a point code c-c-* is not allowed).

ANSI, ITU international, or 24-bit ITU national point codes using the value “c” can be entered by specifying only the ni=c parameter (for ANSI point codes), zone=c parameter (for ITU international point codes), or msa=c parameter (for 24-bit ITU national point codes), and the nc, ncm, area, id, ssa, and sp parameters can be omitted.

The pcst and npcst parameters, for specifying the ITU international and 14-bit ITU national spare point codes, cannot be used with point codes containing the character “c”.