Excel 2007 : How do you create summaries / collapse items down to summary

[glen40]

Apologies if this has been asked but I have been sent a spreadsheet where the items can be collapsed or expanded by clicking the - or + sign in the left hand and top margin. What is this called so that I can search for a help item to create my own.

regards

[glen40]

Hi, typical, I now found what I was looking for, it is 'Outline (group) data in a worksheet' will give it a go following Office help.