Also appeared as "Music-Hall" (with a dash).
Argentinian label, owned and distributed by SICAMERICANA S.A.C.I.F.I. (Sicamericana Sacifi).
On the 60's and 70's (as "Music-Hall") released records from artist of the genre/style Music Hall. On early 80's, just as as "MH", most of releases were from Argentine artists. During late 80's, mostly were compilations (VA) of European artists.

Music Hall cat works the following way:

The first number defines the type of release - The other four numbers define the cat.

X.XXX - LPs produced from artists signed with the label
1X.XXX - LPs not signed with the label or artist not directed associated with Music Hall.
3X.XXX - Singles
6X.XXX - EPs
9X.XXX - LP Reissues.
11X.XXX - Stereo - Available when an LP had Mono and Stereo versions on sale
50-XX.XXX - Licensed, adopted for all released on a short time between circa 75 to circa 78. May also come in 60, 70 or 80

Do not add MH- to the catalog. That's part of the matrix's side identifier. The dot separating most cats was added circa the 2000th national release.