Purchase email subject

This is the subject of the email that is sent to customers when they make a purchase. Available variables are:

• <TMPL_VAR NAME=PRODUCT_NAME> the name of the Product in System -> Configuration or in custom API
• <TMPL_VAR NAME=SERVICE_EMAIL> email of the person set as contact in the rate plan of the customer
• <TMPL_VAR NAME=PURCHASE_NAME> the name of the purchased product, as in the column 'name' from table 'products'
• <TMPL_VAR NAME=IS_PRODUCT> Boolean, will take the value 1 if the purchase is of type "Product", 0 otherwise
• <TMPL_VAR NAME=IS_CALL_TIME> Boolean, will take the value 1 if the purchase is of type "Call time", 0 otherwise
• <TMPL_VAR NAME=IS_CALLS> Boolean, will take the value 1 if the purchase is of type "Concurrent calls", 0 otherwise
• <TMPL_VAR NAME=MINUTES> the number of minutes purchased
• <TMPL_VAR NAME=QUANTITY> the quantity of the product purchased
• <TMPL_VAR NAME=XXX> Name of any column xxx from table 'customers', referring to the customer that is invoiced
• <TMPL_VAR NAME=YYY> Name of any column yyy from table 'people', referring to the person that is set as contact for the customer that is invoiced