What does 'top=?' mean in a FASTA header?

[quantic]

I pipeline I am working with has a step which says:

echo "Rename OTU sequences. All OTU with 'top=?' regarded as 'Other'"

And then calls a python script that filters all sequences from a FASTA file containing 'top=?' on its header. I am wondering what this does exactly as I can't find any documentation about it. Thanks

[Brian Bushnell]

This is unrelated to fasta headers, and just a quirk of your specific pipeline. If there's no documentation, you'll need to ask the person who wrote the pipeline.