If you do a search you will find info on both Picolo and Coquelet. Both are variations on the mFSK scheme. They were developed back in the 1960s (if I recall properly) for communications of digital (text) data and were intended to provide better performance than RTTY.
You may find this link useful:http://www.wavecom.ch/onlinehelp/WCODE/default.htm?turl=WordDocuments%2Fpiccolomk6andpiccolomk12.htm
73 de Brian, WB6RQN/J79BPL