Lavatory connected to circuit vented branch drain

[tecbuilt]

I have a circuit vented branch drain where all the circuit vented fixtures connect horizontally to the branch drain per code but I have an independently vented lavatory that is connected vertically to the branch drain. The UPC (we use the 2015 version) says additional fixtures (like lavatories) can be connected if they are common or independently vented but makes no mention on the connection method (vertical or horizontal). Am I OK leaving the lav connected vertically?