This character is a Format and is commonly used, that is, in no specific script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Boundary Neutral. When changing direction it is not mirrored. U+1D177 prohibits a line break before it.
The Wikipedia has the following information about this codepoint:
A slur is a symbol in Western musical notation indicating that the notes it embraces are to be played without separation (that is, with legato articulation). A slur is denoted with a curved line generally placed over the notes if the stems point downward, and under them if the stems point upwards.
Prime functions of the slur in keyboard music...are to delineate the extent of a phrase line and to indicate the legato performance of melodies or arpeggiated chords.
Both accents and slurs relate directly to woodwind articulation...(and brass as well) [since they] employ a variety of tonguing effects [which are indicated by use of, "the correct form," of accents and slurs].
[With bowed string instruments] A curved slur over or under two or more notes indicates that these notes are to be connected...Slurs are only partially indicative of phrasing; if an actual phrase mark is necessary (to unite several bow-strokes into a larger melodic idea), it should be notated above the passage with broken lines.
The example below shows two measures in 6 8 with a slur for each measure: