How to re-use document numbers in Vault?
Document numbers are unique identifiers to each document. They are pulled from the document number index and are single-use only. If a document number is changed due to reclassification, the previous document number cannot be used again for any document (new or previous).
The reclassify feature allows for preservation of the document number if the Retain Document Status and Number feature is enabled in Vault. It is up to the user whether the feature is enabled to preserve this number.
The new document type, subtype, and classification must be the same to use the same numbering format.
Vault Help Documentation: