OK, sorry once againg for mess on forum threads.
Format string may contain up to 4 sections defining formatting for positive, negative, zero and text data. What's more: they can describe date, time and fraction formatting. It's a legacy excel feature of course, but unfortunately many excel documents take advantage of this, which means that we cannot simply take the length of format string and subtract 2.
Some examples of valid format strings:
General <- yes, this one too
0.000
0.000;[Red]-0.00
0.000;[Red]-0.00;[Blue]"ZERO!"
0.000;[Red]-0.00;[Blue]"ZERO!";"text:"_@
Hope the attached example will be of some help.
DecimalRead.zip