Classify the relation of question with context to one of these categories: 1) award received, 2) based on, collection, 3) conflict, 4) constellation, 5) convicted of, 6) date of death, 7) director, 8) drafted by, 9) educated at, 10) medical condition, 11) military branch, 12) narrative location, 13) occupation, 14) original network, 15) parent company, 16) point in time, 17) production company, 18) residence, 19) series, 20) service entry, 21) sex or gender, 22) spouse, 23) standards body question.

Context : Turkish Airlines Flight 1951 (also known as the Poldercrash) was a passenger flight that crashed during landing at the Amsterdam Schiphol Airport, Netherlands, on 25 February 2009, resulting in the death of nine passengers and crew including all three pilots. 
Question : On what date did Turkish Airlines Flight 1951 occur?
point in time

Context : ISO 3166-2:NG is the entry for Nigeria in ISO 3166-2, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), which defines codes for the names of the principal subdivisions (e.g., provinces or states) of all countries coded in ISO 3166-1. 
Question : Who set the standards for ISO 3166-2:NG?
standards body

Context : The MG 42 (shortened from German: Maschinengewehr 42, or ``machine gun 42'') is a 7.92×57mm Mauser general purpose machine gun designed in Nazi Germany and used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II. It was intended to replace the earlier MG 34, which was more expensive and took much longer to produce, but in the event, both weapons were produced until the end of the war. 
Question : In what year did MG 42 enter service?

service entry