Tag represents allowed tags in a search query. The tags in the query
should be followed by a colon character. Only NameString tag is allowed
to have more than one word.
For example `g:Hom. sp:sapiens`, `n:Homo sapiens`
const (
AllMatches Tag = iota Author
DataSourceIDs
ParentTaxon
Year
NameString
Genus
Species
SpeciesAny
SpeciesInfra
)