How was Beowulf transcribed and translated, such that you see instances like this: http://i.imgur.com/iujDtHF.jpg vs the transcription "lofdaédum sceal in maégþa gehwaére man geþéön." (via http://www.heorot.dk/beowulf-rede-text.html, et al).
Specifically, things like the missing "m" on "lofdaedū". I'm assuming the "l" was burnt off of the original manuscript, as with the "þ" of "geþéön".
So which of these is correct? Where did the extra "m" come from? Or is it just a modern transcription, like replacing "f" with "s" (à la Shakespeare)?
The line above the u is an abbreviation mark, usually for a missing m.
If you have more questions about transcribing Old English I'm happy to try to answer them.
Paleography is a weird, arcane science. There are all kinds of abbreviations and suspensions which are used in manuscripts like the lined u to represent the -um ending, and there are variations between manuscripts, so that the transcription is done based on the collected manuscripts available. In Old Icelandic, for example, you have Njála with over 60 intact manuscripts and fragments, and Laxdæla with over 100 intact and fragmentary manuscripts, each of them with their own variations. There's a lot of work involved.
Beyond that, translation is an art in and of itself. You have to balance between a strict/close translation of the original (which might not make much sense to modern readers) and a looser, more poetic translation, which will be easier to read but won't be as 'pure' as the source material.
