HMS Forms
=========

"HMS" stands for Hours-Minutes-Seconds; when used as an angular
argument, the interpretation is Degrees-Minutes-Seconds.  All
functions that operate on angles accept HMS forms.  These are
interpreted as degrees regardless of the current angular mode.  It is
also possible to use HMS as the angular mode so that calculated angles
are expressed in degrees, minutes, and seconds.

The default format for HMS values is `HOURS@ MINS' SECS"'.  During
entry, the letters `h' (for "hours") or `o' (approximating the
"degrees" symbol) are accepted as well as `@', `m' is accepted in
place of `'', and `s' is accepted in place of `"'.  The HOURS value is
an integer (or integer-valued float).  The MINS value is an integer or
integer-valued float between 0 and 59.  The SECS value is a real
number between 0 (inclusive) and 60 (exclusive).  A positive HMS form
is interpreted as HOURS + MINS/60 + SECS/3600.  A negative HMS form is
interpreted as - HOURS - MINS/60 - SECS/3600.  Display format for HMS
forms is quite flexible.  See HMS Formats.

HMS forms can be added and subtracted.  When they are added to
numbers, the numbers are interpreted according to the current angular
mode.  HMS forms can also be multiplied and divided by real numbers.
Dividing two HMS forms produces a real-valued ratio of the two angles.

Just for kicks, `M-x calc-time' pushes the current time of day on the
stack as an HMS form.