In addition to its native file format, which it saves in file bundles with a .vlsong extension, VocalEasel is capable of importing and creating a number of other file formats.
All available file formats are displayed with the Open... menu item.
Like much of the functionality of VocalEasel, file importing is fairly new and little tested. To make file reporting more comprehensive and reliable, please report any import problems as bugs.
MusicXML <http://musicxml.org> is capable of representing a huge variety of sheet music, and VocalEasel only understands a small subset of this: A single melody, with an optional harmony and lyrics. Examples of this kind of MusicXML can be found at Wikifonia <http://www.wikifonia.org>
VocalEasel should be capable of importing most Band-in-a-Box <http://www.pgmusic.com> files, although not all styles may work correctly at this point.
Lilypond <http://www.lilypond.org> is capable of representing a huge variety of sheet music, and has a rather general purpose input format with procedural elements that is not easy to parse. Therefore, VocalEasel is only capable of importing very simple Lilypond files.
To export a VocalEasel song in a different format, use the Save a Copy As... menu item and select the format from the popup menu. File exporting should be fairly reliable already.