The convention of typists using two spaces after a full stop only came about because of the limitations of the fixed spacing for characters and spaces. Whether it should persist depends entirely on what you're typing into. If it's a fairly dumb piece of software, which interprets a space as "add this much white space", then it may or may not be appropriate to use two spaces. If it's something which will lay the document out (such as TeX or LaTeX), then clearly there's no need. While we're wedded to documents containing layout markup rather than functional markup I guess double spacing will persist. Dunstan