Definition: Under as in below the surface of
Less than. Eg: "under the age of 18"
under as in lower in rank, power, or authority
Eg: "The other two projects will receive funding under the government.."
Gloss: paper[t] cl-paper pen[t] cl-pen[loc]
English equivalent: a pen under the paper
Use a passive (e.g. left-handed) classifier for the paper and a dominant classifier (e.g. right-handed) for the pen if you're right-handed signing.