[Koha] How to use Item Type ?

[SATISH]

it might be a silly question, but  I believe,  similar question has been
asked in the forum before but I did not get clarified.

since "item type" is used for defining circulation rules, "Item Type"
(952y) at "Item" level sounds good.
What is the necessity of  calling "Item type" (942c) at Record level
instead of calling it as "record type".
Circulation rules are defined for ITEMS which are associated with a RECORD.
since record  holds biblio detail, and items are meant for circulation, is
it meaningful to call "item type" at record level?
Is it necessary to define 942c? what happens only 952y exists?
Kindly clarify me to understand this item type.

with thanks
Satish MV
Librarian
GEC Hassan
Karnataka.