Value 2 (& 5):
As number is never marked on the noun itself, bare nouns, lacking an article, are neutral with regard to number.
Although we do not exclude the possibility, we did not find a proper example with a singular definite article (Value 4)
The definite plural article (Value 7) is extremely rare in this context; the indefinite singular article (Value 8) less so.
Source: Schumann 1783: 83
Source: Schumann 1783: 130
Source: Schumann 1783: 130
Source: Schumann 1783: 66
Source: Schumann 1783: 195