chromium/third_party/blink/web_tests/external/wpt/webvtt/rendering/cues-with-video/processing-model/regions/support/viewportanchor_y_50_percent.vtt

WEBVTT

REGION
id:1
viewportanchor:0%,50%

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