While this answer is specific, it could be clearer, IMO: Reviewing the Intel Manuals at https://software.intel.com/sites/default/files/managed/a4/60/253665-sdm-vol-1.pdf Section 4.2.2.
We can see that the 64 bit significand of Double Extended Precision refers to an 80-bit floating point representation, and the 53-bit significand of Double Precision refers to a 64-bit floating point representation. I think if we just leave the 64/53 bit numbers in the comment, the reader might think we are not using 64-bit floating-point representations. https://codereview.appspot.com/577450043/
