Comment by ddingus

BTW, some contributors to that forum thread are incorrect about interlace being about the number of scanlines.

Interlace requires there be one half scanline.

Whether there are an odd or even number of scanlines can impact color phase shifting, depending on whether the source signal is phase shifting the color burst.

Older machines, such as the 8 bit Apple 2, did not phase shift at all so color artifacting would be predictable and useful. Even vs odd scan lines would affect precise frames per second only.