PeopleSoft record key field vs Oracle record primary key

Hi,

In otherwords, how PeopleSoft record key field information stored at the Oracle database level..?  I want to query oracle metadata table ALL_CONSTRAINTS to verify or validate if a particular PeopleSoft record has any key fields. Assuming in Oracle database level it will be stored as Primary key. My understanding is that, at Oracle database level, primary key field will have constraint_type as "P", but it appears that all PeopleSoft record fields are stored as "C" check constraint on a table. Coud someone explain this or any other alternateway to identify the key fields..?  I know we may be able to