The function
field_info returns the sizes and other attributes passed in
to the field at its creation time.
The attributes are: height, width, row of
upper-left corner, column of upper-left corner, number off-screen rows, and
number of working buffers.
The function dynamic_field_info returns the actual size of the field, and
its maximum possible size.
If the field has no size limit, the location
addressed by the third argument will be set to 0.
A field can be made dynamic
by turning off the O_STATIC option with field_opts_off.