The Timed Text Working Group has published a W3C Recommendation of TTML Profiles for Internet Media Subtitles and Captions 1.0 (IMSC1). This document specifies two profiles of TTML1: a text-only profile and an image-only profile. These profiles are intended to be used across subtitle and caption delivery applications worldwide, thereby simplifying interoperability, consistent rendering and conversion to other subtitling and captioning formats.