NRT is the Near Real Time detection project. Project goals were simple: Create a system that allowed arbitrary data sources to pass data to specialized detection systems and provide every scrap of data we could back to the incident response teams. NRT’s goal for the first phase of POC was to prove that we could use Snort as a datasource for a system. The end result was the capability to thread out (non-blocking) detection of PDf files, handling the common evasion techniques for PDF files.”]
Source: https://blog.talosintelligence.com/2010/04/new-detection-framework.html