Hi PC is performance criteria.
It's your practice - what you do set against a list of guideline 'standards ie criteria. It can be what your assessor would observe or witness you doing on their setting visits to you and also what you write about.
You can view all the unit pdfs through this thread -
CCLD level 3
Element CCLD 301.1 Develop relationships with children
Performance criteria
This is the national standard which you must meet:
1. Interact with children in a way that helps them feel welcome and valued
Hth xx