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 !   

Spool-mapping

It is a classic Global Mapping exercise presenting ^SPOOL as Class / Table

Background

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.

Solution

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.

The structure of Spool

• the global ^SPOOL is local to your namespace
• fist subsccript is a UNIQUE Document_ID
• second subsctipt is a line number UNIQUE to the document.
• both together form the IDkey

Details: The Spool Device
https://docs.intersystems.com/irislatest/csp/docbook/DocBook.UI.Page.cls?KEY=GIOD_spool

Example

Article in DC