Fortis is a term that refers to voiceless consonants as their production is stronger than the production of lenis consonants. They need much more effort. Lenis is a term referring to voiced consonants that need less effort in their production. As for phonemic transcription, both should be enclosed between slashes to make them different from the letters used in ordinary spelling.
Some researchers however use the terms "fortis" and "lenis" as convenient labels that don't necessarily have anything to do with articulatory effort. In her PhD thesis on pre-aspiration, for instance, Ní Chasaide (1985) makes a very good point that it can get a bit cumbersome to talk about phonetically voiceless "voiced" plosives, etc., and so she resorts to "fortis" and "lenis" to cover the phonologically distinct series.
I'm not entirely sure though what exactly you'd like researchers to contribute to this discussion with based on the title of the discussion: are you hoping for files being uploaded?