MPEG4: Field coding in MPEG4 interlaced stream

[partham]

Does mpeg4 have the provision field-interlacing as well?

Lets say an mpeg4 encoder has to create an interlaced video from an input stream.

What i mean is that - could the encoder choose to encode top and bottom fields of a frame separately (field-coded-interlace), or together (frame-coded-interlace)? If possible, the output of the former will be a 'frame', top half of which will contain one field, while the bottom half will have the other field. Is that possible?

If the above is possible, then mpeg4 standard should contain some "identifier" to know whether an encoded video is frame-interlaced or field-interlaced. For example, in case of mpeg2, we have a parameter called "picture_structure". What is the 'corresponding' parameter in mpeg4?

Please see what i mean is MPEG4 Part-2 (Visual), and not MPEG4 AVC.