Negative values on screens, I/O templates for screen fields

When you try to display a field with negative content on a screen,
you can run into the error : "FX015: Sign lost."
As a solution you could change the I/O template for 
the field from "____________" to
"___________V" (with +/- sign).

Althoug SAP tells "... The template of an input/output field
on a screen may only consist of underscores. At runtime, this is       
replaced with a suitable template (for example, for entering a date).
"(message 620(37)), you can change the template, eg. for negativ values (V)
and separators.