[BRLTTY] Typing all characters Focus 40

[Frans-Willem Post]

Hello,

Using BRLTTY 5.3.1 on Ubuntu 16.04.3, with Orca 3.18.2 and a FS Focus 40 
Blue over USB.

I would like to know if it is possible to type ALL characters from my 
braille table using the dots 1-8 on the display?

I use my own table, based on the standard European table from 
http://www.braille.ch/eb-erl-g.htm

For most characters this works: simple letters, capital letters, digits. 
I can even type some accented characters, but not all.

For example: I can type 'a' using Dot1, 'A' using Dot1+Dot7, '1' using 
Dot1+Dot6 and 'á' using Dot1+Dot6+Dot8 - but not 'ë' using 
Dot1+Dot2+Dot4+Dot6+Dot8. Why not?

Thank you,

Frans-Willem Post
The Netherlands