Advantage Concepts
During a transaction, it is legal to close tables. If the table, memo file, and index files associated with the table were never modified, the files will be closed. If they were modified in any way, then the files will be cached closed. Cache closed means the file will not actually be closed until the transaction is committed or rolled back.
Some file close functionality is illegal when performed within a transaction, however. The illegal close functionality is: closing all tables, closing an index files, and closing all index files. If these close functions are used, a 5063, "The command is illegal within a transaction" error is generated.
If you position directly to a record that is being appended/inserted by another application during a transaction using a "go to" or "go to bookmark" operation, the user will be positioned to one record past the end of file and the EOF flag will be set to True. This behavior exists because records appended/inserted during another transaction are "invisible" to all other users until that transaction is committed.
Explicit record and file unlocks are legal during a transaction, but the unlock operations will not actually be performed until the transaction has completed. The unlock operations will be "stored" to be performed when the transaction has been committed. Unlocks are not allowed during a transaction because corresponding updates to those records/files could not be made during the commit of a transaction if the lock(s) did not exist.