: Indicates that this specific file is a software update (patch) rather than the base game, with "31118418" likely being the build or version identifier.
The string appears to be a standardized filename for a Nintendo Switch update file . This nomenclature is common in gaming and modding communities to provide specific metadata about a digital file at a glance. Breakdown of the Filename
: It is important to note that you should only use NSP files for software you legally own. Downloading files from unauthorized third-party sources is considered copyright infringement.