@ap86: AssetAttributeType(2305) does not permit user-defined values. The intention is to provide a standard taxonomy of terms. AssetAttributeGrp is not intended for your examples anyway if you take a look at its external codelist. It has items such as “DeliveryType”, “DeliveryMethod” etc. This is below the actual asset, i.e. it provides attributes for a given asset.
The examples you give are probably already covered by the risk taxonomy as part of the Instrument component, e.g.
AssetGroup(2210)= 2 (Commodities)
AssetClass(1938) = 5 (Commodity)
AssetSubClass(1939) = 15 (Energy)
AssetType(1940) = “Oil” or “Natural Gas” or “Electricity”
“The company providing the rating. How do we set a fix tag on this?” If you are a FIX member, then you can join working groups (https://www.fixtrading.org/working-groups/), e.g. MiFID Reference Data Subgroup which can submit extension proposals to the FIX Global Technical Committee.
I am not familiar with your term “call schedules”. Take a look at the ComplexEventsGrp component if that is what you are looking for. FIX does cover payment and delivery schedules for OTC derivatives.