When a file reaches the press, the RIP separates it into plates. One plate per ink. A CMYK stroke would end up split across the cyan, magenta, yellow, and black plates as ink that actually prints. A spot-color dieline, by contrast, separates cleanly to its own tooling plate that the die-cutter reads, but no ink ever hits the substrate.
That's why a dieline drawn in 100% Magenta or "Black" looks like a dieline on screen but prints a visible line on press. The structural geometry is correct; the color setup is wrong.
Different RIPs and prepress pipelines expect slightly different names. The most common:
When in doubt, ask your print provider what they expect, then match the name exactly, including capitalization.
The top reasons a file gets sent back from a print shop:
Terminology is loose across the industry. "Dieline" and "cut path" are usually interchangeable. "Keyline" can mean either a dieline or a visible outline stroke in the artwork itself. Ask what your print provider means before assuming. "Safety line" or "safe area" is different entirely: an inner boundary indicating where live text and logos should stay clear of the die edge.
Upload your file and Preflight will tell you whether the dieline is on the right layer, in the right color, and named the way the press expects.
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