I want to know the answer to the following question:
What does the Opening of the Triodion derive from?
All the background I'm provided with is that "In Greece Carnival is also known as the Apokriés (Greek: Αποκριές, "saying goodbye to meat"), or the season of the "Opening of the Triodion", so named after the liturgical book used by the church from then until Holy Week.". Is that enough to answer the question?
Answer: yes