Definition of some jargon?
 

Hi guys,
I'm reading through some literature at the moment and am having a couple of problems understanding some of the jargon. Could someone please help me by explaining what is meant by a "time-accurate" and/or "semi-implicit".

I'm quite new in this field and have a very vague idea what these terms mean. If someone could clarify them a little I'd be very grateful.

Many thanks
T