This is why on vinyl releases on discogs we use baoi tags descriptions like runout matrix label side a and runout matrix runout side a.
Matrix runout vinyl.
A matrix or stamper number is a code etched inside the end groove area found on each side of a vinyl lp.
Consisting of numbers and or letters the code may indicate recording dates specific takes and even the system of recording.
On cds there is no groove or wax so matrix area is the term we like to use here on discogs and it seems to be fairly common among collectors elsewhere.
Label matrix number optional label code optional runout matrix number optional example 1.
Practically since day one the inside track or runout groove of a vinyl record or 78rpm disc has been the domain of the matrix number an alphanumerical code either stamped or handwritten into the wax to help pressing plants assign the correct stamper and label to each side of the record.
Matrix numbers and other run out information can also be extracted from the whole run out inscription and added as further matrix.
Though these numbers were originally intended for internal use by a record pressing plant you can use them to.
Lp jacket front cover.
It is so we know where the text appears.
Starting with the front cover and working clockwise we have the title artist label catalog number note the one on the spine next to 5 both should be entered and a company credit which is optional.
This information should all be added to one matrix number field.