The share of orders received conforming to requirements, first time, as a percentage. The higher, the better.
Why this indicator
A reliable chain is a chain that delivers conforming: non-conformities are delays, rejects and extra costs. A good chain approaches 90% conformance, which is therefore the floor of the "comfort" zone for this indicator.
Where to find the figure
If you use supply chain software, this percentage is in it. Otherwise, look in your supplier quality tracking: register of receipts and non-conformities.