when placing a TOS defline and a item is picked to place the Tos defline. If the item has a Z coordinate then this can be assinged the TOS block. the defline will be a 0 but the blocks will be elevated (although it looks normal) this will usually raise once and then the error will occur even if you put a new defline in. tos id missing

When clicking the abacus to enter a length, you get this error;

Unhandled exception has occurred in a component in your application.  If you click Continue, the application will ignore this error and attempt to continue.

Index and length must refer to a location within the string.  Parameter name: length