Making fields of custom table uneditable.

Hi,

I have created a custom table and assigned it to a t-code.

My requirement is that whenever I execute this tcode...my table should be opened as maintainable table with few columns uneditable, so that user is not able to change their values.

My problem is that all my columns are in editable mode. Please help me out in making out those columns uneditable.

Thanks in advance.

Parul