&gt; Vast majority of uses of cal apply to dates &gt; 1900 (and I&#x27;d say a significant amount is &gt; 2000)<p>According to what?  Your use?<p>&gt; &#x27;cal 16&#x27; should require a flag saying &quot;Yes, I know what I&#x27;m doing, this is the actual year&quot; and&#x2F;or print the corresponding year for this century (being explicit, when printing, to which year it refers to)<p>The command wants a year number as input.  &#x27;16 is an ambiguous abbreviation that gains meaning only within context.  As the command can&#x27;t ask you what you meant, the default behaviour is sane.