chromium/third_party/blink/web_tests/external/wpt/webvtt/rendering/cues-with-video/processing-model/regions/support/single_line_top_left.vtt

WEBVTT

REGION
id:1
viewportanchor:0%,0%
regionanchor:0%,0%
lines:1

00:00:00.000 --> 00:00:05.000 region:1 align:left
This is a test subtitle