What determines the last 4 digits of a created Service Request Number?

Summary:

When the system creates HR Help Desk Service Request Numbers, I understand it utilizes the SVC_PUID_PREFIX value as a prefix to the SR and the SVC_PUID_FORMAT following the prefix. The question is what the determining criteria is for the rest of the Service request number. For example, one SR may be created with the SR number 00004001 and the next SR created will be 00006003. Why aren't these submitted SR's created numerically (i.e., 00004001, 00004002, 00004003).

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