Imagine Band-in-a-Box having a built-in midi soft synth sound module that does not require any programming by the end user, is invisible to the end user, is operating system agnostic and can be customized by PG Music as needed to work within the framework of their programs.
+++ FluidSynth +++ is an open source, real-time software synthesizer based on the SoundFont 2 specifications. FluidSynth itself does not have a graphical user interface, but due to its powerful API, several applications utilize it. FluidSynth has even found its way onto embedded systems and is used in some mobile apps.
Cross platform support (Linux, macOS and Windows to name a few) SoundFont 2 support
SoundFont 3 support (vorbis-compressed SF2)
Realtime effect control using SoundFont 2.01 modulators
Limited support for Downloadable Sounds (DLS) Level 1 & 2
Playback of MIDI files Shared library which can be used in other programs Built in command line shell
It appears from the website the software is updated about twice a year.
+++ HERE +++ is a link to the online documentation.