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When CX-One installed, there are online manuals that also install.
There are some restrictions on Reusable Files.
Check the CX-Programmer Operation Manual, pdf pages 114, 135 and 211 for more information.
gtsuport
When any structure definitions exist on the data type view, you cannot select the Function Block (Ladder) Generation menu item or the Reusable File | Save as... menu item in all sections.