What I need to know is whether I need to make it clear in my log book what flights are sole ref to intruments. My log book only has the column for IFR.
You can write what you like in your log book, it's your log book, provided that you log the minimum required by law.
Of course if you're saving up hours for the grant of some licence or rating you need to record whatever is needed for that licence or rating - there are so many of these that you can't expect your log book to have a column for each possibility or to give a definition of each in the notes in the front.
I'm currently doing an IMCR course, so am using the column headed "instrument flight" for IFR and the column headed "instructional hours" for sole-reference-to-instruments - it's not difficult to cross out a column heading and write in something else.
I don't have a column headed "floatplane flying" either but I manged to record it to my satisfaction!