I'm sure this is somewhat simple but haven't been able to wrap my head around it, so here it goes:

How to segment the following example of a macro
"x1 x2 x3 x4 y1 y2 y3 y4 z1 z2 z3 z4"

into the following macros

"x1 x2 x3 x4"
"y1 y2 y3 y4"
"z1 z2 z3 z4"

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Additionally, can you set a macro name in relation to the value of another one?

Ex: say I have

local counter_i: "98".

Can I generate a macro called year_98 by referencing it to `counter_i'?

Have tried to so by coding local year_`counter_1' --as I would do, for example, to name a variable, But stata keeps telling me that is an invalid syntax.

Thanks in advance for your help, and apologize in advance for any lack of technicalities or ambiguities in my terminology.

Best,

Sergio.