General question on how to name ports depending on python.

Hello,

currently I work on porting Python modules that depend on a installed finance/trytond. Basically,
trytond itself is a Python module provides the framework and a core server component that these
modules use.

During the works I found out that the ${PYTHON_PKGNAMEPREFIX} is useful for properly describing
the dependencies within a ports Makefile. That's why I changed the Makefile of trytond to contain
	
	PKGNAMEPREFIX=  ${PYTHON_PKGNAMEPREFIX}

which causes the pkg name to be

	py27-trytond-2.4.1_2

As the result, I can refer the trytond dependency in all ports that require it these way:

	BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}trytond>=2.4.0:${PORTSDIR}/finance/py-trytond

My question is now about the naming if the ports directory. I have seen examples where python modules
have the "py-" prefix and others don't. When the output of pkg_info|grep tryton shows:
	
	py27-tryton-2.4.0_1 The Tryton Client
	py27-trytond-2.4.1_2 A three-tiers high-level general purpose application platfo
	py27-trytond_account-2.4.1_1 The Account Module for Tryton
	py27-trytond_account_invoice-2.4.1_1 The Account Invoice Module for Tryton
	py27-trytond_account_product-2.4.1_1 The Account Product Module for Tryton
	py27-trytond_company-2.4.0_1 The Company Module for Tryton
	py27-trytond_country-2.4.0_1 The Country Module for Tryton
	py27-trytond_currency-2.4.0_1 The Currency Module for Tryton