lcFilter = [country = '] + ALLTRIM( this.Value  ) + [']
SET FILTER TO &lcFilter
** It means
SET FILTER TO Country = 'SomeCountryName' && Then Country must be Character, This.Value must be Character too


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lcFilter = [country = ] + TRANSFORM(this.Value) && w/o [']
SET FILTER TO &lcFilter
** It means
SET FILTER TO Country = 5 && Then Country must be Numeric, then This.Value must be numeric too