Related smells: Improper Alignment
There are many formatting mistakes one can make when creating a grammar without proper tool support [LDTA-2012-Zaytsev] [SCAM-J-2009-LammelZ11]. Mostly they revolve around mistypings, misspellings, misalignments, etc, and result in actual incorrect constructs in extracted grammars. However, there can be other, more subtle smells within formatting of a grammar, that do not change the way the machine processes it, but do change the way a tired grammarware engineer may understand it. The most canonic example of misleading formatting would be (mind the colon, not a semicolon, following ghi):
abc :
def;
ghi:
jkl;
mno :
pqr;