Thanks @AndrewAMD. This bit of the Python code would seem to support your guess:
# Calculate RollLong and RollShort in account currency, for the quantities used by Zorro
financing_pos_size = defaultdict(lambda: 1, {'CURRENCY': 10000}) # Everything but CURRENCY defaults to 1
data['RollLong'] = data['financing.longRate']/365 * \
data['Price'] * \
data['type'].map(financing_pos_size) * \
(data['currency']+'/'+ACCOUNT_CURRENCY).map(conversion_rate)
data['RollShort'] = data['financing.shortRate']/365 * \
data['Price'] * \
data['type'].map(financing_pos_size) * \
(data['currency']+'/'+ACCOUNT_CURRENCY).map(conversion_rate)
Would still appreciate @jcl's thoughts. Of course "we don't code to undocumented things" is an appropriate response, but perhaps the plug-in could handle these via a "use at your own risk" option?
Thanks.