To force it to string you have to append some non numeric character ! 
but this one is then part of the subscript as $c(0) or whatever you append
in addition, you break the numeric sort and change to string sorting.

USER>set s1=111,s2=444,q="."
USER>set a(s2)=1,a(s1)=2,a(s1_q)=3,a(s2_q)=4
 
USER>zw a
a(44)=1
a(111)=2
a("111.")=3
a("44.")=4

Do you still expect some echo?
Or is the question meanwhile just out of date?

Do you still expect some echo?
Or is the question meanwhile just out of date?

 
USER>set s1=111,s2=444
USER>set a(s2_$c(0),s1_$c(0))=77
USER>set a($c(0)_s1,$c(0)_s2)=99
USER>zwrite
a("111","444")=99
a("444","111")=77
s1=111
s2=444
USER>

"save it from the class " ?  whatever that may mean .... ?

An object might not fit well a Global with a reasonable number of nodes.
But by SQL you get it line by line. check this:   Show Global by SQL SELECT

you may try

USER>write $tr("abcdefghijkl","abcdxefxghxijxkl","2022-03-29T15:10:00+0100")

SendRequestSync   is an object method that requires an object as the base.
##class(Ens.BusinessService).SendRequestSync(   works for ClassMethods only.
You need an object instance of Ens.BusinessService to call it.
##class(Ens.BusinessService).%New().SendRequestSync( 
might be a dirty workaround

I guess all you need is to redirect the ouput of %RCMP  to some %Stream of SPOOL:
In addition, you have %RCMP in your installation and just pick out what you need.

• %XML.GlobalCharacterStream  extends %Library.GlobalCharacterStream
• therefore it has method FindAt()

method FindAt(position As %Integer, target As %CacheString, ByRef tmpstr As %CacheString = "", caseinsensitive As %Boolean = 0) as %Integer

Find the first occurrence of target in the stream starting the search at position. It returns the position at this match starting at the beginning of the stream. If it does not find the target string then return -1. If position=-1 then start searching from the current location and just return the offset from the last search, useful for searching through the entire file. If you are doing this you should pass in tmpstr by reference in every call which is used as a temporary location to store information being read so the next call will start where the last one left off. If you pass caseinsensitive=1 then the search will be case insensitive rather than the default case sensitive search.

Copy to String may help but is limited by MAXSTRING size.
There you may use [  (=contains OPERATOR) or $FIND() function

Don't mix up SQL predicate %CONTAINS  with [  (string contains operator)

in System Mgmt Portal / Operation / Database  you find a Free Space view