Unknow for me,Mam Seitziana PL.Centr 99

Dear friends
I have a question.
On the label from a old plant, i see the name: Mam.Seitziana ? PL. Centr 99
What means PL.Centr 99 ?
Last one: Is this a Mam Seitziana??
Thanks for your expertise,
Greetings'
Joseph

M. seitziana is an old name and appears to refer to a variant of M. magnimamma from Hidalgo.
Your plant looks like M. magnimamma to me, and it is a very variable species, which is why so many names have been used for different forms, to the extent that many, like seitziana in my view, are valueless. If you had a collection number then maybe you could sensibly use seitziana, as it does appear to have been validly published, just a redescription of an existing species,

PL. Centr 99 isn't a reference that I recognise, sorry.

Hallo Chris !
Thank you for your extensive expertise! I am very happy with it! Maybe someone knows anything else, else let me just, such as it is.
Have a nice day,
Joseph