How is “mechanism” split (hyphenated) at the end of the line?
http://www.merriam-webster.com/dictionary/mechanism says mech·a·nism
but
http://dictionary.reference.com/browse/mechanism?s=t says mech·an·ism
.
Where can I split the word at the end of a line? Is the difference between the on-line sources about British versus American English (which one is which), or is one simply wrong, or what circumstances do I have to pay attention for to determine which one to choose? (If there is a third, better, free on-line resource, naming its url for future use is also welcome!)