Data about data.
For example, a FileAllocationTable is MetaData. The 'control' file in a DebianLinux .Deb is MetaData.
The Journal in a JournaledFileSystem? is MetaData and it is though the cunning using of this MetaData that such FileSystems get their edge.
In the field of Information Retrieval, MetaData refers to data about a document. For example, the Title, Author, Date, etc are all MetaData about the actual document. Bibliographic records help look-up based on MetaData.
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