Summary
This article outlines the differences between Asset quantity, duration and number of units. The differences are important to note for accurate project tracking and accounting.
Asset Quantity
The Asset Quantity is how many of the Elements you want booked. In the example below, you want 3 generic "Editor - STAFF" elements booked on your Order.

Asset Duration
Plan hours measures the duration of hours between the start and end dates of the booking. This works well for bookings that have small ranges, however for longer bookings (e.g. a week) it will show the entire cumulative hours for that week.

# of Units
The number of units booked is typically used for financials since it is tied to the unit of measure (UOM) for cost and/or revenue. In the example below, even though the duration hours are 23.98 hours, the actual number of unit hours booked are only 8 hours as a resource does not typically work 24 hours a day and therefore that number should not be used for actuals and accounting.
