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For example, only if the domain \ project \ user_id is an EXACT match to the entries in the database will that PSL be used.

1. The project id may have associated sub-projects that will be represented as project  string. If a sub-project is identified but only the project exists in the table then the project PSL would be used.The project may not have an entry in the table and in that case any project  would be designated the PSL of the domain.
2. If a general domain PSL is not available in the table and only a specific project is associated with the domain in the table, then any incoming messages not associated with that project will return an error.
3. In the table, the "@" character is used to represent the absence of an entry (rather than a blank or a null).
4. In the explicit string and in the <project_id> an "@" can be used to optionally represent a blank column.

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