pub fn unit_row(gene: &str, modality: &str, subunit: &str) -> Box<str>Expand description
Format a channel-less UNIT row {gene}/{modality}/{subunit}.
One producer names a unit with no channel, because its contrast lives ACROSS
the units rather than within the row: the APA poly-A mixture,
{gene}/apa/{component} — usage is relative across the components of a gene,
so no component has a counterpart channel.
SNP allele counts were the second such producer, splitting alt and depth
across two same-shaped matrices that a consumer had to open together. They
are now BAF, channelized on ALT/DEPTH inside one matrix.
Such a row is indistinguishable from a gene-level one under
parse_feature_row: both are three fields, and the subunit lands in the
channel slot. A consumer has to know which matrix it is reading. Prefer
feature_row wherever the modality does have two channels.