SAP Framework PO's with/by quantity

Is it possible to create a Framework PO by quantity.

So for example.

We Raise a framework for 150 days @ £500 per day = £75,000 limit.

The IRs would then be processed, specifying quantity and amount.

However, would doing this prevent us from setting up frameworks without a quantity?

Basically I would like to know if its possible to create Framework Orders by quantity/value limit as well as only value limits.

Currently my company can create Framework Orders via only value limits.

If it is possible to create FO's via Quantity, please could you kindly provide me with the steps to configure this functonality.

Thanks