Welcome to ECN,mate.
With respect to your question regarding flexible cords, a flexible cord,is a cord which affords flexibility by virtue of the number of strands in the individual cores of
the flex, normally, a flex has a whole lot of smaller conductors, to enable bending and twisting of the cord.
As opposed to a cable used for fixed wiring,
this is not meant to be stressed or bent like a flex would be.
Hope that I have been at least some help,
not sure of your Codes over there though.