Legal requirement to ensure correct size/weight is delivered?

Dear Fellas,

I am helping my friend to get BRC. He is manufacturer of Tortilla which are packed by number and in two different sizes (in different packs). Wandering any one could help to understand, apart form verifying correct number of tortilla in the pack,is there any other legal requirement to ensure correct size/weight is delivered otherwise it could effect nutritional information. Is there any clear legislation on that?

Just to clarify my friend want to pack by number not by weight.

Would appreciate any help.

Thanks

Martin 

I previously worked at a mushroom farm & we had a BRC audit where they wanted to raise a non-conformance because we used an over under scale to ensure packsize was the labelled weight, however we always added a little extra just to make certain that the weight was over & that was the auditors cause for concern. They called their office and because it was not a hazard/food safety concern it was not raised.