·     The edge of month <X> is actually the first day of the next month.

·     The HAAB is commonly present but optional (e.g. absent in  PAL TI Sarcophagus Lid #28).

·     Grube-TLDoY is a paper which discusses the fact that in examining 60 inscription dates which involved either a chum (first day) or ti’ haab (last day) expression:

o 35 were chum and 25 were ti’ haab.

o Of these latter 25, more than half involve the month of Yaxk’in.

The former statistic (35 vs. 25) is not surprising, as the imbalance isn’t huge and could just be due to random statistical fluctuation. But the latter statistic is surprising because of all the dates using a ti’ haab expression more than half are used in connection with one specific month, whereas that month only represents about 1/18 of the possible choices – i.e. it occurs far more frequently that one would have expected if the choice were random.