Produce an error from unrecognized residues (otherwise add them as non-carbohydrate entities)
Remove terminal and reducing aglyca before conversion

Produce multiple entries from structures with alternative branches (otherwise use ALT)
Replace repeating subunits with oligomeric insertions before conversion

Produce larger fragments (three or more residues) for branching points
Consider closely-substituted linear fragments (e.g. 1-2 bonds) as branched