For work with DBF files I use DBFNavigator

there were some problems. namely when opening one DBF file I want to change the code page. but it cannot be made. for some reason the field is blocked (Enabled = by True). though I have other DBF files created through VFP and if to open them in DBFNavigator there a field which displays the code page for some reason actively. It would be desirable to understand as to force the field "code page" to be active?