Dynamic Custom Fields

[Jorge Arturo Tijerina García]

Hi everybody

I´ve been working for a while trying to understand how the dynamic custom
fields work.
No success at all. There is not enough documentation.
What I am trying to do is to have 2 custom fields (combo boxes), one with 3
options called "Area". Other one called "services" with 5 options.
What I want is when a user select an option in the "area" combo box, the
"services" combo should show 3 of the 5 options that corresponds to the
"area" I selected. When I select the other option in area combo box, the
services should show the rest 2 options.
In other words, I need a dynamic combo box that is the result of the
selection of the "area" combo and based on these values the "services" combo
will be filled with the options corresponding with the area combo value.
I guess Dynamic Custom Fields do this for me, but, because of the lack of
docs, I was not able to make this work a all... I tried to create backends
for the custom fields but when I relate the backend with the custom field I
only get blank pages.
I am really lost, does anyone have this working?, any ideas or examples? I
really need to have this in function but .. without luck!!.
Appreciate help .. ASAP.
Regards

-- 
Jorge Arturo Tijerina García
Software Engineer