PRST table

Can anyone help me on the PRST table in SAP?

It is project - bom link table, so I suppose it should store headers of BOM.

However for a particular project in our quality system it is storing the pillars of a material which is attached to a WBS.

The pillars are however not visible in the project but get fetched from the table on the condition of wbs and plant.

Thanks in advance

Yatin.