Frame & Interlaced Confusion

Hello,

I have a big question about frame, field, intelace, non interlace and pairs macroblocks.

The "PicInterlace" parameter, in the reference software config file "encoder.cfg", refers to interlaced image sequence nature. The "MBInterlace" parameter refers to "mb_field_decoding_flag" parameter of the Standard. 

I´m confused about "frame_mbs_only_flag", "field_pic_flag" and "mb_field_decoding_flag" Standard parameters.

Is the following paragraph right? The "frame_mbs_only_flag" parameter equal to 1 specifies non interlaced image sequence nature. The "field_pic_flag" parameter equal to 1 specifies that the slice has interlaced nature and "field_pic_flag" equal to 0 specifies that the slice has non interlaced nature. The "mb_field_decoding_flag" parameter equal to 0 specifies two (pair) macroblocks frame (not interlaced) and equal to 1 specifies two (pair) macroblocks field (each one interlaced).

If the video is interlaced. Is it possible that one macroblock has one field in the even rows and the other field in the odd rows (interlaced video)?

Other questions...

For the following cases, what would the values be for the indicated parameters?

Case 1: Non interlaced video, no pair macroblocks. 
Parameters: "PicInterlace", "MBInterlace", "frame_mbs_only_flag", "field_pic_flag" and "mb_field_decoding_flag"

Case 2: Non interlaced video, pair macroblocks. 
Parameters: "PicInterlace", "MBInterlace", "frame_mbs_only_flag", "field_pic_flag" and "mb_field_decoding_flag"


Case 3: Interlaced video, no pair macroblocks (macroblock has one field in the even rows and the other field in the odd rows). 
Parameters: "PicInterlace", "MBInterlace", "frame_mbs_only_flag", "field_pic_flag" and "mb_field_decoding_flag"

Case 4: Interlaced video, pair macroblocks (even macroblocks of one field and odd macroblocks of the other field).
Parameters: "PicInterlace", "MBInterlace", "frame_mbs_only_flag", "field_pic_flag" and "mb_field_decoding_flag"

Thanks.

Ángel