Defining swing

I think it was created using MuseScore, but I can't work out how.

Thank you for your suggestions. FWIW, my interest in this came because it was given as an example of how a score editor is more powerful than ABC editors. I couldn't see how it was done. I think you're very likely right and it was an imported cheat. I suppose I was wondering if it was possible to substitute note symbols for characters in text, or something of the sort.

Cracked it:
1. Create the small notes above the stave using note input - voice 2, which allows you to input the dotted-quaver/semiquaver pair and the triplet coupled quaver/semiquaver as a separate set of notes independently of the main tune notes. Make the note pitch about the G above the stave but not higher so you don't introduce ledger lines.

2. Make the Inspector palette visible (F8) and adjust the vertical offset of the voice 2 notes (use 'chord' select option) until they are well above the stave. Reverse the stem direction so they are all pointing up (select the beam and press X). Adjust the horizontal distance between the two pairs so there is room to insert an = sign. Finally use the palette to make the notes 'small'.

3. Insert the = sign by selecting a note head and then inserting the = as stave text, again adjusting the horizontal and vertical spacing to get the = to the correct location.

4. Finally, select unwanted characters, e.g. rests in voice 2 and made them invisible (option in Inspector palette)

NB - creating the notes in the way I've described will make them audible if you decide to play back the score, so to fix this, select each of the voice 2 note heads in turn and turn off the 'play' option for each of the notes in the inspector palette.

Not something I would want to do everyday...and not my work :-)