To repeatedly insert a group of lines in various places within a document, you can yank (or delete) the lines into a named buffer. You specify named buffers by preceding a command with double quotes (") and a name for the buffer. For example, to yank four lines into the named buffer a, type "a4yy". You can use several different buffers. For example, you might also delete text from one location and add it to several others. To delete 12 lines into the named buffer b, type "b12dd".
To insert the text, precede the p or P command with n, where n is the named buffer. For example, to insert the lines saved in buffer b, type "bP".
You can overwrite named buffers with new lines. The buffers are saved until you exit vi.
When you use named buffers, you can safely delete and yank other text without affecting the lines you have already saved in the named buffers -- unless, of course, you purposely overwrite the named buffer.