what does loading on back of pre-amp for phono mea


have a british fidelity mvt pre-amp. on the back there are 2 sections.one for mm,the other for mc=there are also input openings marked loading by each,one ==im using mm ,but dont know what the loading inputs are for any one out there know???
1940lw
thanks for the response,but there are inputs marked loading ,next to both mm,and mc
The loading inputs are for loading resistors. Both MM and MC cartridges have ideal loading that is less that the stock 47K of the preamp itself. So (wisely) they made a provision.