Subtitles ttxt and TextBox

[susanap]

Hello,
I'm young with ttxt file, but I appreciate your help. I've seen any TTXT samples. All have <TextStreamHeader> <TextSampleDescription>
<TextBox>
<TextSample sampleTime="00:00:00.000" ...>

Now TextSample has startTime but I don't know how set duration, for example I'd like write a subtitle from 00:00:00 to 00:00:05, and after I hide the Textbox from for example the moment 00:01:00 which I will write other subtitle.
Do you know how can I do it?

Thanks you

[bond]

insert a new textsample with an empty text at the time you want the textsample before to vanish