What is "isilo"

iSilo is a document reader available for Palm OS, Pocket PC, Windows Mobile Smartphone, Symbian UIQ, Symbian S60, and Windows CE Handheld PC handhelds, Windows computers as well as Apple iPhone, Android, Windows Phone 7 and HP webOS smartphones. iSilo has direct support for reading these document types: iSilo 4.x, iSilo 3.x, iSilo 2.x, Palm Doc, and plain text files (.txt). However it has largely fallen out of use due to its one-way nature — documents can be converted to iSilo format, but not back out for editing. Other formats, such as epub use open standards, are easily edited or converted, and achieve similar compression rates.