tarx files -- what is it ?

Hi!

Could You help me?

I found ftp://updates.qnx.com/pub/ph_cyrillic_sup/updates/Ph_Cyrillic_sup.tar

This archive contains:

Ph_Cyrillic_sup.tar size-0 bytes (???)
phcyr-1.00-01.tarx
phcyr-1.00-02A.tarx

Explain me, please – what is it ?
What can I do with it ?
What is the tarx archive ?


Respectfully Yours,
Vasilii