In mm. 342 and 382 of the last movement of his Piano Quartet n. 3, Op.26, Brahms writes G.P. over one measure's rest (with no fermata). Is the intention that this General Pause should last exactly one measure, or should it be interpreted as being at the players' discretion regarding the length?
If of discretionary length, is it within bounds to make the rest shorter than the number of beats in a measure? What if there were a number of measures indication, e.g. 2 along with the G.P. — wouldn't that mean a G.P. of exactly 2 measures?
G.P. (General Pause) or L.P. (Long Pause)
The generalpause or the long pause serve the same function, and are identical in function to the fermata when used over a rest or barline. The function of these pauses is to create a silence for a period of time at the discretion of the performer (or conductor with an ensemble). As indicated in the name, these are intended to be pauses of longer duration than any of the others. These marks are always shown over rests. They also interrupt the normal tempo of a composition.
(Source: OnMusic Dictionary / Pause Markings)
Is the explanation above saying that a G.P. over a measure's rest is identical to a fermata over the rest? Just beneath the illustration, the source makes a distinction when explaining a cesura, and a cesura with a fermata:
The use of the fermata combined with a caesura indicates a much longer silence.
As I see it, a measure's rest with a fermata should generally be longer than a plain measure's rest. Put another way, can a G.P. be exactly the length of the rest, or must it always be longer, i.e. with an implied fermata? Is it more than a reminder that no one is playing?
General Pause Indication in orchestral scores that all the players are silent at that point.
(Source: New Oxford Companion to Music)
That is how I always understood it, as heads up/confirmation that no instrument is playing — not per se an indication of the length of the pause.
General pause In a score for an ensemble piece, "G.P." (General Pause) indicates silence for one bar or more for the entire ensemble. The marking of general pauses is relevant, as making noise should be avoided there—for instance, page turns in sheet music are avoided during general pauses, as the sound of players turning the page would be audible by the audience.
(Source: Wikipedia / Rest (music) / General pause)