Specifies the index of the tab that is to be initially selected when the web page is shown.
Note: Clicking on the tabs in the Design view alters this value to the index of the currently selected tab. Since you will do this routinely while designing your tab pages, you will need to remember to select the first tab again (or whichever tab you wish to be initially selected) before saving your work.
Any integral value between 1 and the number of tabs (inclusive) or the name of a field that will contain the tab index at run-time.
If the value specified is less than 1 or greater than the number of tabs, then no tab is initially selected. In many applications of tab pages, this will not be desirable.