Description of problem: There is not any appdata.xml/metainfo.xml file available in the Xnec2c package. Because of this, Xnec2c cannot be found and/or installed using the GNOME Software application or another package manager UI based on AppStream. Steps to Reproduce: 1. Open GNOME Software. 2. Type "xnec2c".
This bug appears to have been reported against 'rawhide' during the Fedora 27 development cycle. Changing version to '27'.
It looks like this issue was fixed in Fedora 27.