"Select" for non-key fields

Hi experts,

jsut a short question:

I have the link

/sap/opu/odata/sap/ZTEST/mara

to read MARA.

I know I can select a specific material with link

/sap/opu/odata/sap/ZTEST/mara(123456789)

for material number 12345679.

Is it also possible to use non-key fields, for example

/sap/opu/odata/sap/ZTEST/mara(MATKL='01')

to get all MARA entries with MATKL = 01?

Thanks for an update

Michael