When saving a def-file from CFX-Pre the following error message can appear: ERROR A problem was encountered with a CFX data file. Unable to write the requested IO string array data set. What = G/NAMEMAP Where = EVERY When = 0 Primary file = /name.def [open] The reason for this error is a name string (boundary name, interface side, …) which is above the limit of 80 characters. The solution is to reduce the length of the names to max 80 characters. The limit of 80 characters is documented and in the CFX-Pre GUI it is also ensured when creating new boundaries, but it cannot be ensured in all cases. Check the following scenarios: 1. When creating a new boundary in the CFX-Pre GUI the name field only allows an input of max 80 characters. However, with the “Rename” function or by the CCL-Editor the name can be arbitrarily changed. 2. When creating an interface the interface name is also limited to 80 characters. However, each side of the interface in the connected domains get a suffix added, i.e. ” Side 1″ and ” Side 2″, which adds another 7 characters. So if the interface name is above 73 characters, then the interface sides will automatically be above 80 characters, resulting in the above error message. 3. When running CFX-Pre in batch with a user defined CCL, the length cannot be checked.