How to use Colon (:) to resolve a condition in Macro

[SASuserlot]

I am trying to resolve the condition of the macro in my code.  I have the two conditions  where I want to  output the error in log based on the input macro variable 'fld' . If it starts with numeric then it have to put one condition otherwise it need to put another error in log ( most of my names with 'SC' if its not numeric

In my example fld= 101-281 then I am expecting  to print 'ERROR: 101281 starts with Numeric", My second one is mostly my name starts with 'SC' how can I control the second condition using the ':' colon in the % if condition to print 'ERROR:&dsn ( numeric values of the 'fld' name)  starts with alpha character SC" 

I am able to use ':' in dataset condition but not sure how to use it the macro, instead of writing every  name in the 'If' Condtion.

Thank you for your inputs.

%macro check (fld=);
*%global output dsn;
%let output = %sysfunc(compress(&fld, "-"));


%if &output ^=: SC %then %do;
	%let dsn= %substr(&output.,1,6);

data _281;
	putlog  "ERROR: &dsn starts with Numeric";
run;

%end;

%else %if &output = :SC %then %do;
	%let dsn= %substr(&output.,3,6);
data _109;
	putlog  "ERROR:&dsn starts with alpha character SC";
run;
%end;

%put &output &dsn;


%mend;

%check (fld= 101-281);
%check (fld= 121-281);
%check (fld= SC100426);
%check (fld= SC100843);
%check (fld= SC102126);
%check (fld= SC105143);

[SASKiwi · Accepted solution]

You can't use '=:' in macro logic. It is simply not available. You can do the same thing though like this:

%if %substr(&output,1,2) ^= SC %then %do;

[PeterClemmensen]

Unfortunately, the colon operator is not in the list of macro operators. Would be cool though.