It's short for cross-assembly phage. It keeps showing up in metagenomic studies (especially when doing cross-assembly of the metagenome), but it's mostly unchar

It's short for cross-assembly phage. It keeps showing up in metagenomic studies (especially when doing cross-assembly of the metagenome), but it's mostly uncharacterized (or at least was, a handful of years back. Not sure about now). So the name implies that we can detect its presence and gets its genome with genetic analysis, but have very little idea of what it actually is or does.