The .set tabs command clears previous tab stops and specifies tab stop locations at specified column position.
.set tabs tabstop{,tabstop...}
| tabstop | (up to 30) The tab stops must be greater than 0 and in increasing order. They indicate tab stop positions relative to the left margin. |
Tabs are only in effect in nofill mode. The left angle bracket is the left-tab character that causes the next word to start at the next tab position. The right angle bracket is the right-tab character that causes the next word to end at the next tab position. If a tab character displays at a point in the line where no further tab stops have been set, the tab character is ignored.