TLK

From NWN1 Custom Content Guide

File extension for TalkTable files. The most common file one would associate with is the dialog.tlk that is in your NWN game directory.

Its format is a line number followed by text. The number is used in place of text in various NWN game resources, particlarly in 2DAs. The number is commonly referred to as a StringRef (or StrRef).

i.e.:

0	Bad StrRef
1	text
2	text
...