Attachment of channel elements

An attachment assembly comprising at least one elongate channel element and at least one male fastening element comprising a shank to fasten the channel element to another structural element,

• the elongate channel element having a bottom, sidewalls extending from the bottom substantially at right angles and an upper side opposite the bottom, wherein the upper side of the channel element comprises flanges which extend from the respective sidewalls towards each other and which delimit between them a longitudinal slot extending over the length of the channel element,
• wherein the bottom has at least one aperture formed in it for passing through the shank of the male fastening element, and
• wherein the bottom at its side facing the upper side of the channel element has an upstanding collar portion that is monolithically formed with the bottom of the channel element and that extends at least partially around said aperture, and
• wherein the male fastening element has a head that has a circular groove in the side where the shank is located, said collar portion being receivable in said groove in the head so as to mutually lock the head and the bottom in position at said aperture.