I use the ~ and the - symbols and numerically start with a 01 after the -.
All databases will lump 10 with 1 and 20 with 2, it's been like that for years, so for numbers below 10 add a 0 to them (01, 02 etc).
As a former business owner that used databases for stock control my stock (asset) codes were all alpha numeric, the first letter was the parts unit location, second letter was shelf or bin row and third letter was the location of the bin along the row followed by a stock number. Same logic can be applied to track marks.
For trainz I use a town location code for the start, then a district location if needed, then track track number, then location along the track in the up or down direction of travel.
e.g
HAN~SSSY 04-01 (Hanfield~South Sorting South Yard Track 01-Trackmark number)
HAN~SSSY 05-10
This should always show in alpha-numerical order in the dropdown list.
I usually add a name indicator in surveyor for the location, because as an oldun I can't always remember what my codes mean :hehe:
A picture will explain better..
A large sub section of a large sorting yard in a town beginning with HAN..you can see the correct Alpha-Numeric display in the Drive Via pull out at the bottom right.
I hope this helps