Idea about release years of Sonorop label (French)

[neowave]

Hi all, now found some Sonorop records entertaining and decided to find out the release years of the records, but saw that Discogs doesn't have any approximate year of release listed but what I noticed:

On each record there is a so-called X PARTX which is very similar to the year of issue, e.g.

https://www.discogs.com/release/5673210-Jean-Claude-Pelletier-Orchestre-Ballets-TV
Jean-Claude Pelletier Orchestre* - Ballets T.V.
Label:
SONOROP - SONO 3039

has X PARTX 59.605 and X PARTX 59.606.
1959?

and Jean-Claude Pelletier Orchestre* - Ballets T.V. SONO 3039 is the last of the series where Microsillon 33 ⅓ is written.
And the inscription about microsillon 33 turns is a notable mark of the 1950s,
Usually such inscriptions were out of use by the early 60s as far as I can remember.

The next release
https://www.discogs.com/release/9780347-Orchestre-G%C3%A9o-Daly-Vibra-Marimba-Clavecin-And-C
Orchestre Géo Daly - Vibra, Marimba, Clavecin And C°
SONOROP - SONO 3040 XY 60.469 - 60.470 no Microsillon 33 ⅓ inscription.
1960?

Also saw on discogs
https://www.discogs.com/release/9772592-Orchestre-Luis-Pena-Untitled
Orchestre Luis Pena* - Untitled


SONOROP - ESPL 1002-1005
which have YPARTX 62.989- 62.995, which may also indicate the year and release number, perhaps they were placed at the end of the sequential numbers as an exceptional distinction from the rest of the Sonorop releases for 1962?

[delatecla]

Hi, comparing those XPARTX numbers with similar ones from other French releases, I would say
SONO 3001-3027 are from 1965
SONO 3029-3037 from 1966
SONO 3039-3051 from 1967/68

[stackjackson]

I've always wondered why so many library labels didn't list release dates either in their catalogues or on the labels themselves. Very odd, in my view.

[tim gueguen]

Perhaps they thought not listing a release date would prevent users from thinking an album was out of date and not using it.

[neowave]

Hi, comparing those XPARTX numbers with similar ones from other French releases, I would say
SONO 3001-3027 are from 1965
SONO 3029-3037 from 1966
SONO 3039-3051 from 1967/68

How did you compare them, and what Lp's or releases did you compare it to

P.S. I am googled XPARTX is a system of numbering of french releases. Good.

[stackjackson]

Perhaps they thought not listing a release date would prevent users from thinking an album was out of date and not using it.

Good point, tim. Makes sense.