flpsed is a WYSIWYG pseudo PostScript editor.  "Pseudo", because you
can't remove or modify existing elements of a document.  But flpsed lets
you add arbitrary text lines to existing PostScript documents.  Added
lines can later be reedited with flpsed.

Using pdftops, which is part of xpdf one can convert PDF documents to
PostScript and then add text to them using flpsed.  flpsed is thus useful
for filling in forms, adding notes, etc.

Features:

    * Add arbitrary text to existing PostScript documents.
    * Reedit text, that has been added with flpsed.
    * The overall structure of the PostScript document is not modified.
      flpsed only adds the additional text.
    * Batch processing (no X11 required) to modify tagged text lines that
      have been entered interactively with flpsed before.  This is very
      useful for repeatedly filling in forms.
    * Text lines can be imported from other flpsed-modified documents.
    * Import and export PDF.  Therefore it can be used as a PDF editor.

WWW: http://www.ecademix.com/JohannesHofmann/#flpsed