Marc is a library cataloging format - see for information.

Marcedit is a windows only application but can be run on linux with ubuntu. On ubuntu need to install all the YAZ modules - search the software centre for YAZ and install all the modules. The version of mono supplied in Ubuntu 12.04 and requires to be upgraded to the developer version of mono

To update mono do

sudo apt-get install mono-develop

Then run the following commands from the directory you installed everything

mono linux_bootloader.exe
mono MarcEdit.exe

This will install a working version of MarcEdit and allow you to edit and convert files under Ubuntu 12.04.