Top-to-top leading measures the spacing between lines of type from the top of one line to the top of the next line. This is different from Bottom-to-bottom leading, which measures the space between lines from the type baseline. If you use Top-to-top leading, the first line of type in a paragraph is aligned flush with the top of the bounding box; if you use Bottom-to-bottom leading, space appears between the first line of type and the bounding box.
The leading option you choose does not affect the amount of leading between lines, only how the leading is measured. (See Specifying leading.)
Note: Top-to-top Leading and Bottom-to-bottom Leading are not available for vertical text.
To specify how leading is measured:
Select the paragraphs you want to adjust.
Choose Top-to-top Leading or Bottom-to-bottom Leading from the Paragraph palette menu. A check mark indicates which option is selected.
