Two-column mode lets you conveniently edit two side-by-side columns of text. It uses two side-by-side windows, each showing its own buffer. There are three ways to enter two-column mode:
2C-two-columns). If the right-hand buffer doesn't already exist, it starts out empty; the current buffer's contents are not changed.
This command is appropriate when the current buffer is empty or contains
just one column and you want to add another column.
2C-split). The current buffer becomes the left-hand buffer, but the text in the right-hand column is moved into the right-hand buffer. The current column specifies the split point. Splitting starts with the current line and continues to the end of the buffer.
This command is appropriate when you have a buffer that already contains
two-column text, and you wish to separate the columns temporarily.
<F2> s or C-x 6 s looks for a column separator, which is a string that appears on each line between the two columns. You can specify the width of the separator with a numeric argument to <F2> s; that many characters, before point, constitute the separator string. By default, the width is 1, so the column separator is the character before point.
When a line has the separator at the proper place, <F2> s puts the text after the separator into the right-hand buffer, and deletes the separator. Lines that don't have the column separator at the proper place remain unsplit; they stay in the left-hand buffer, and the right-hand buffer gets an empty line to correspond. (This is the way to write a line that “spans both columns while in two-column mode”: write it in the left-hand buffer, and put an empty line in the right-hand buffer.)
The command C-x 6 <RET> or <F2> <RET>
2C-newline) inserts a newline in each of the two buffers at
corresponding positions. This is the easiest way to add a new line to
the two-column text while editing it in split buffers.
When you have edited both buffers as you wish, merge them with
<F2> 1 or C-x 6 1 (
2C-merge). This copies the
text from the right-hand buffer as a second column in the other buffer.
To go back to two-column editing, use <F2> s.
Use <F2> d or C-x 6 d to dissociate the two buffers,
leaving each as it stands (
2C-dissociate). If the other buffer,
the one not current when you type <F2> d, is empty,
<F2> d kills it.