Guides use the same unit as the rulers and object controls. They snap artwork at exact printed positions, scale with the canvas, stay with this sheet, and never appear in production output.
PMP smart guides appear while moving artwork. When Margins is on, artwork also snaps to the selected product’s safe-print boundary. Use the Snap button to turn guides off for unrestricted placement, or hold Alt only for the current drag. Nudge, X, Y, W, H, and rotation use real printed measurements, so movement stays exact at every product size. On macOS, use Command in place of Ctrl.