Secureline are the choice here also, even though they have a short
life.  One thing to be aware of, the RED secureline pen markings on a
 cassette will be totally lost during processing, had a whole research
project go into the garbage because of this and my language habits 
went totally downhill, with closed doors!  USE THE BLACK pens.  The red
pens followed the ruined cassettes/tissues into trash can!

Or we use soft leaded pencils, Tissue Tek had some that worked, but 
a #2 pencil will work, press hard! 

Gayle Callis