Frame constraints
In Dorico Pro, constraints define the relationship between each of the four sides of a frame and the corresponding page margins.
Frame constraints lock each side of frames to the corresponding page margin, meaning you can change the page size, or the area that is defined by the page margin, while keeping the frame in proportion. For example, a music frame that fills the entire height and width of a page has constraints on all four sides. All sides have an inset of zero, which means that the edges of the frames are in line with the page margins. If you change the size of the page, the frame size changes accordingly so that it always fills the page, whatever the current page size.
Page size and margins are set for each layout in .
If you remove a constraint from one side of a frame, that unlocks that side of the frame from the page margin, meaning you can determine a fixed width/height that prevents that side of the frame from adjusting, even if the page size changes.
Example
If you have set a frame for a header, you might want the left and right sides to be locked to the left and right margins of the page. For the top side of the frame, you might want to lock it to the top margin, but want to keep the height of the header fixed. In this case, you can remove the lock to the bottom margin and specify a fixed height by moving the side of the frame, or by entering a value in one of the value fields in the Properties panel.
In the Frames section of the formatting panel, you can define the constraints for all types of frames that are available in Dorico Pro. All new frames have active constraints on all sides by default. You can unlock two sides of a frame to specify a fixed width or height. For example, if you remove the lock to the top margin, you can also remove the lock to the right/left margin.