Reference: www.md-subs.com/line-spacing-in-ssa, aegisub.org/docs/3.1/ASS_Tags, and www.tcax.org/docs/ass-specs.htm

Tags fall into two general categories: those which set a property of the line itself, and those which modifiy only the text following them. \pos, \move, \clip, \iclip, \org, \fade and \fad are those in the first category. Tags in the first category should appear at most once in a line, and where in the line they appear is unimportant. Tags in the second category modify all text after the tag until the end of the line or until the property is re-overridden by another tag. If you can’t achieve the desired result with just one tag, a combination of them, which you put inside a pair of curly brackets

ASS timing format uses centiseconds rather than frames or milliseconds, so when you import from or export to ASS, the round-off errors may sometimes push your timecodes over to the adjacent frame, spoiling your minimum intervals, shot change gaps, durations, etc. {\org(-2000000,0)\fr<value>} Line one, {\r} \N line two: All you need to do to get the desired line spacing is adjust the \fr value. If you want to bring the lines closer, just make the value negative.

\pos(x,y) positions your subtitle at x and y coordinates, \frx, \fry, \frz rotate your text along the X, Y and Z axes correspondingly

\b1 makes your text bold, \b0 to disable boldface again. \u1, \u0 for underline. \fn<name>: \fnArial, \fnTimes New Roman, \fsp changes the letter spacing

\h inserts a non-breaking space, \N inserts a line break, so that the text that follows it goes to the next line

\q<style>: Determine how line breaking is applied to the subtitle line. \q0: Smart wrapping, make each line approximately equally long, but top line wider when equal width is impossible. Only \N forces line breaks. \q1: End-of-line wrapping, fill as much text in a line as possible, then break to next line. Only \N forces line breaks. \q2: No word wrapping, wide lines will extend beyound the edges of the screen. Both \n and \N force line breaks. \q3: Smart wrapping, similar to style \q0, but bottom lines are made wider.

\k family of tags mark up subtitles for karaoke effects by specifying the duration of each syllable: A{\k12}B{\k20} define the character A display time 12 centiseconds (120 ms) and character B display time 20 centiseconds (200 ms).

\fad produces a fade-in and fade-out effect

"Scroll up;y1;y2;delay[;fadeawayheight]" means that the text/picture will scroll up the screen. The parameters after the words "Scroll up" are separated by semicolons. The y1 and y2 values in pixels define a vertical region on the screen in which the text will scroll. The values are in pixels, and it doesn't matter which value (top or bottom) comes first. If the values are zeroes then the text will scroll up the full height of the screen. The delay value can be a number from 1 to 100, and it slows down the speed of the scrolling - zero means no delay and the scrolling will be as fast as possible. When delay is greater than 0, moving one pixel will take (1000/delay) second. fadeawayheight and fadeawaywidth parameters can be used to make the scrolling text at the sides transparent. Similarly, "Scroll down;y1;y2;delay[;fadeawayheight]" can be used.

“Banner;delay” means that text will be forced into a single line, regardless of length, and scrolled from right to left accross the screen. The delay value can be a number from 1 to 100, and it slows down the speed of the scrolling - zero means no delay and the scrolling will be as fast as possible.