Operand &1 has non-linear weighting &2

What causes this issue?

You use operand &v1& with operand category TQUANT in a rate step to
which the <DS:DE.TIMECONTRL>period control</> &v3& is allocated. This
period control is only permitted if the operand has a linear weighting
procedure.

System Response

&v4& is inconsistent and cannot be saved.

How to fix this error?

Allocate the period control <ZH>exact number of days</> to the step, or
choose a linear weighting procedure for operand &v1&.

Error message extract from SAP system. Copyright SAP SE.