Pat Hasler:
You should by law draw a line at start and finish of duty 
Not true, there is no legal requirement to draw lines on the disc. However there is also no law forbidding it either and it may be a company policy or the advice given by VOSA in your area, either way it’s not law though.
Pat Hasler:
The line however must not come into contact with the trace mark
True, if lines or any other information are drawn they must not obliterate the trace.
Pat Hasler:
Any other form of writting such as reasons for over hours or vehicle changes must be written on the rear side of the chart
Again not true. Although the normal place for such things is the back of the disc there is nothing stopping you from recording this information on the front.
From the VOSA website
WHERE SHOULD MANUAL ENTRIES BE MADE?
If a chart has a special place to make entries, usually on the reverse side, this is where they should be made. But they can be made anywhere on the chart provided they are clear and do not obliterate other recordings.
Pat Hasler:
It is very rare that anyone will get prosecuted for not drawing them
It would be more than rare as it would never happen. Because no law has been broken by not drawing the lines a prosecution would have no legal basis.
Pat Hasler:
but they are recomended to cover any duty taken when the card is not in the tacho
Not just recomended but in this case the information is legally required to record duty time while not having access to a vehicle with a tacho head.
Coffeeholic what is the general practice for writing on Tacho’s for European work? I’ve heard lots of reports that the French don’t want any writing on the front and the Germans want the tahco to be in for 24hours.
If you start at differant times each day how do you make sure that your card is only in for24 hours?
Correct, the French will relieve you of large quantities of your hard earned cash if you draw on the front of the tacho.
The Germans want to see a 24 hour record of your activities, that doesn’t mean each disc has to be in for 24 hours though. If when you park up one night you know you will be starting later the next day than you did that morning remove and complete the disc in the head and insert another one to record your daily rest. Start and finish place and kilometre readings are the same and in the space where you normally calculate the kilometres done I write ‘Daily Rest.’ I then change that disc for a fresh one for when I start the next morning. I’ve been doing it that way for years and it has never caused a problem with the BAG or the authorities in any other country, including the UK. This method is safer than risking the disc running to more than 24 hours as that can attract a fine as well.
The only time I don’t keep a full 24 hour record is when I’m week ended. I’m in Germany this week end and I completed the tacho when I finished at lunchtime yesterday and the tacho head will remain empty now until Monday morning when I go back to work.
I also think it’s down to the particular company and the way they work. Walkers Crisps like you to put SDR and EDR (with vertical line showing the time), because you can be waiting for hours before you go out in a vehicle. My current boss doesn’t like me to mark the recording area of the tacho anywhere, because your tacho’s in and placed on crossed hammers as soon as you get into work. You could obscure information on the trace by writing across it if your not careful (and you’d be suprised how many arn’t).
However if I’m sat for any length of time without a tacho in (which is very unusual) before going out, then I’ll do it. Similarly when I end my shift. Personally I’d draw it (the horizontal line) on the back, where the proper markings are as to avoid obscuring the trace and can see where your comming from Nomad.