Principal photography in practice
It begins on the first shooting day and ends at wrap. It is the most expensive part of a production because the whole cast and crew are paid and most equipment is rented at the same time. Work done by a smaller team before or after, such as landscapes or inserts, is called second unit or additional photography.
On commercials and corporate videos people simply say the shoot.
Where it lives in CrewDesk
In CrewDesk a production in principal photography is in the Shooting stage. The dashboard counts productions in this stage so a company knows at a glance how many crews are out.