Data set dataset_:

[cdubs]

I have a question about the function of "_:"

data all_claims;
	set  dataset1
		dataset2
		dataset3_:;

I don't see a dataset entitled "dataset3_:" elsewhere in the code, though I do something close to it. 

%macro dataset3 (year_start=, year=);
		data dataset3&YEAR. (where=(mdy(12,31,&YEAR_START.)<svcdate<=mdy(12,31,&YEAR.)));
			set have;
			rename date1=date2;
		run;
		
		proc means data=dataset3&YEAR. noprint nway missing;
			class var1 var2 var3;
			var var5 var6;
			output out=clean.dataset3_&YEAR. (drop=_:) sum=;
		run;
	%mend dataset3; 

Any idea what dataset3_: is in reference to? 

[ChrisBrooks · Accepted solution]

What's important here is the colon after dataset3_ - that means all data sets starting with the name "dataset3_" like so

data dataset3_2015;
	set sashelp.class;
run;

data dataset3_2016;
	set sashelp.class;
run;

data dataset3_2017;
	set sashelp.class;
run;

data want;
	set dataset3_:;
	
run;

What you end up with it all three data sets appended