I.on [美 ɑn, ɔn, 英 ɒn]介词on often appears as the second element of certain verb structures in English (count on, lay on, sign on, etc). For translations, see the relevant verb entry (count, lay, sign, etc).
The basic advantage of single context planning is context plans draw on transparent perma-trace paper can be overlaid for re-interpretation at a later date.