[Koha] About example with the 952 field

[zolot]

Hi All,

In "Koha 3.14 Manual (en)" there is the "Tag 952 Subfield constraint" table  (see section '4.1.4. Edit
Framework Subfield' of the chapter '2. Administration'). 

Why exactly 952 ?   
Is it accident ? Maybe, this field randomly has been selected as an example of the ordinary field ?


Or, maybe, this is more essential, the 952 field is a special field in the Koha system ?
For instance, not for cataloging but for a management ctalogues.

Regards,
Gennady