Deanne,
This is referring to the financial dimension formats specific to importing/exporting via data entities. There can-be different formats depending on the type of entity as well.
For example, you can have one format for budget register entries, a different one for budget planning entries, and yet another for ledger entries – with the “default” covering everything else. You can have multiple of each type configured, but only one (of each type) may be active at any time.
You can often run afoul of this when importing via the Excel add-in – as importing budget entries (for example) may have a different allowed format than importing journal entries.
This configuration is found in General ledger/Chart of accounts/Dimensions/Financial dimension configuration for integrating applications.