A little bit late ---- This is answered in SAS Note  43902 : http://support.sas.com/kb/43/902.html Most of the SAS Language and all of the SAS Macro Language are 'free format' giving the ability to format and indent code for better readability. When compiling a macro, the SAS Macro Facility strips out any formatting (spaces, line breaks, tabs, etc.) in the model text to minimize the size of the stored text. DATALINES, CARDS, and PARMCARDS statements are not free format. When the SAS Macro Facility compiles these statements, it removes the formatting, which would very possibly move data into incorrect lines and/or columns. This can cause incorrect results and is the fundamental reason for the restriction. ... View more