Two-Column Editing

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:

C-x 6 2

Enter two-column mode with the current buffer on the left, and on the right, a buffer whose name is based on the current buffer's name (tc-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 contains just one column and you want to add another column.

C-x 6 s

Split the current buffer, which contains two-column text, into two buffers, and display them side by side (tc-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.

C-x 6 b buffer RET

Enter two-column mode using the current buffer as the left-hand buffer, and using buffer buffer as the right-hand buffer (tc-associate-buffer).

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 C-x 6 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, C-x 6 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.)

It's not a good idea to use ordinary scrolling commands during two-column editing, because that separates the two parts of each split line. Instead, use these special scroll commands:

C-x 6 SPC

Scroll both buffers up, in lock step (tc-scroll-up).

C-x 6 DEL

Scroll both buffers down, in lock step (tc-scroll-down).

C-x 6 C-l

Recenter both buffers, in lock step (tc-recenter).

When you have edited both buffers as you wish, merge them with C-x 6 1 (tc-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 C-x 6 s.

Use C-x 6 d to disassociate the two buffers, leaving each as it stands (tc-dissociate). If the other buffer, the one not current when you type C-x 6 d, is empty, C-x 6 d kills it.