What key element must be included in administrative reports related to informants?

In the context of administrative reports regarding informants, including an administrative code number is critical because it provides a systematic way to track, categorize, and reference various reports related to informant activity. The administrative code number serves as a unique identifier that enhances the organization of data, ensures consistency within the reporting structure, and aids in maintaining the integrity of the files related to informants. This allows for better accountability and easier retrieval of information when needed for compliance, investigation, or evaluation purposes.

The other options, while they might contain useful information in different contexts, do not serve the essential function that an administrative code number provides. Personal identification details may compromise informant confidentiality, and listing previous informants could risk exposing operational methods, while noting the time of day for compliance checks is not a fundamental element required for administrative purposes specifically related to informants.