Use of Property "Editing" in Pages using C/AL Code.

Hello All,

I need help with the following:  

In Dynamics Nav 2013, I have a Page type CardPart, where I have set a source table to manage data, on page I added the fields from that table. I do some field validations using C/AL Code, with respect to enable editing in a field if the condition introduced in a previous field is met and if is not met I want to disable the field.

I tried to do, in the following ways:

•  Field.Editing(FALSE);
•  CurrPage.Field.Editing(FALSE);

However, in both ways I get the following error:  

    ---------------------------

    Microsoft Dynamics NAV Development Environment

    ---------------------------

    You have specified an unknown variable.

    Editing

    Define the Variable under 'Global C / AL symbols'.

    ---------------------------

    Ok

    ---------------------------

Could anyone tell me how can I?.

Best regards,

Marlon T. Ramirez