(crucial decision point): From the plot of the film Sliding Doors.

sliding door (plural sliding doors)

1. A door that opens and closes by sliding to the side; sometimes one of a pair.
   • 1958 April, “Diesel Railbus for British Railways”, in Railway Magazine, page 275:

     Constructional features of the railbus include the use of rubber suspension for axlebox/underframe and underframe/body mountings, the use of B.U.T. power transmission equipment, many components of which are interchangeable with those on British Railways standard railcars, power-operated sliding doors, and an absence of normal sidebuffers or drawgear.

   • 2012, David Walliams [pseudonym; David Edward Williams], Ratburger, London: HarperCollins Children’s Books, →ISBN:

     However, before Zoe could open the first cage, Burt’s van, looking decidedly the worse for wear, came thundering into the warehouse, smashing the huge metal sliding door into the air as it did so

   • 2019 October 23, Pip Dunn, “The next king of Scotland”, in Rail, page 50:

     Thus, the ScotRail plan was to totally refurbish the trailer vehicles, with new sliding doors and a host of other improvements.

2. (figurative, attributive) Denotes a crucial decision point at which outcomes diverge depending on which of two courses is followed.

   sliding door(s) moment, sliding door(s) decision

• up and over door

• longidorids