19:47 Jan 9, 2010 

Gentlemen, thank you for the explanation. I admit that this is not my field!

19:41 Jan 9, 2010 

Hi Rokia & Lamis: I don't think there is an error. This is probably either a GIS software or an accounting software? A tool tip needs to be displayed over either an aggregate or a measurement. The right answer would be determined if we know what type of aggregate or measurement the software produces.
All the best.
YZM

19:41 Jan 9, 2010 

Hi, the idea of the writer is(this is how i understand and i might be wrong) : the tool-tip text has to be displayed in the event of the cursor /mouse is placed over two things, either an aggregate or a measurement.( i hope it helps)

19:26 Jan 9, 2010 

Hi Lamis, I copied this sentence as a it is I changed nothing therein.

19:12 Jan 9, 2010 

Hi Rokia, I feel that the English text is not right. Will you check if it is "or a measurement" or " of a measurement."
A comma is also necessary after the word measurement.