This is a coding example working on IRIS 2020.1 and on Caché 2018.1.3 It will not be kept in sync with new versions It is also NOT serviced by InterSystems Support !
It is a classic Global Mapping exercise presenting ^SPOOL as Class / Table
Device #2 named SPOOL dates back to the predecessors of Caché and IRIS
It was the first "%Stream" like option to buffer output before printing.
It is also the first and till today the most simplest way of output redirection.
This is also an example of a mapped Global.
USE 2 redirects the output into the Global ^SPOOL
You can read the global manually or with some ancient utilities
or use this mapping to access it as class or a SQL table.
Details: The Spool Device