(US) Initialism of Registry of Toxic Effects of Chemical Substances.

Initialism of retrotrapezoid nucleus.

(photography, graphic design) Alternative form of RTL (right to left)

(computing) Initialism of real-time operating system.

Initialism of right to hire. / Initialism of regular trading hours.

Initialism of real time factor. / (computing) Initialism of Rich Text Format. / Initialism of residential treatment facility.

Initialism of return the favour. / (aviation) Initialism of return to flight.

(computing) Abbreviation of release to manufacturing: a stage in the software release life cycle

(military) Initialism of return to base.

Abbreviation of route.