The size of the tab text string can be queried by specifying 0 for the tabTextLen field in the BOOKTEXT data structure. In this way, the application can determine the size of the buffer needed to store the tab text string. The null character at the end of the text string is not included in the returned length.

If this message is sent for a page having both major and minor tab attributes, the notebook returns the text which is associated with the major tab.