![1girl absurdres ahoge bangs belt blonde_hair blush bouquet breasts bridal_veil bride buckle center_opening chain cleavage detached_sleeves eyebrows_visible_through_hair fanbox_reward fate/extra fate/extra_ccc fate/grand_order fate_(series) flower full-length_zipper garter_straps green_eyes hair_flower hair_intakes hair_ornament head_wreath highres holding holding_bouquet jewelry kagachi_saku large_breasts leotard lock long_hair looking_at_viewer loose_belt navel nero_claudius_(bride)_(fate) nero_claudius_(fate)_(all) outstretched_hand padlock paid_reward pink_flower reaching_out ring smile solo strapless strapless_leotard thighhighs unzipped veil wedding_band white_flower white_leotard white_sleeves zipper rating:s score:20 post #3808988](/cdn_image/preview/fa/ac/faacd969e9c4ac201ae2d65a361f31a4.jpg)
This tag is to be used when a zipper in the image (usually on clothing, but applicable elsewhere) has been opened, a.k.a. unzipped.
If the zipper is still in the process of being opened, use unzipping instead.
The 下ろしチャック (lowered zipper) tag on pixiv is often used to refer to a type of unzipped fashion where the chest is left exposed with the nipples covered, oftentimes with the navel also shown.
Saber Bride is a character often demonstrative of this feature, such as in post #2501105.