Request for clarification on encumbered files and avoiding proprietary drivers

[Frederick C. Doe]

Howdy! My sincere apologies if this question is answered elsewhere.

I'm trying to better understand Section 5.4 of the FreeBSD manual:
https://docs.freebsd.org/en/books/developers-handbook/policies/#policies-encumbered

I find the following wording from the FreeBSD manual confusing:
---
1. Any file which is interpreted or executed by the system CPU(s) and 
not in source format is encumbered.

2. Any file with a license more restrictive than BSD or GNU is encumbered.

3. A file which contains downloadable binary data for use by the 
hardware is not encumbered, unless (1) or (2) apply to it. It must be 
stored in an architecture neutral ASCII format (file2c or uuencoding is 
recommended).
---

 From my (admittedly weak) understanding of FreeBSD, closed-source files 
can be broken down into three categories:
1. Kernel Modules (primarily drivers) that operate in kernel-space
2. Firmware that is loaded into hardware on hardware power-up and is 
*not* executed on the system CPU (either in kernel-space or user-space)
3. Software that runs in user-space (games, applications, etc)

A cursory reading would indicate that closed-source kernel modules are 
encumbered, but I'm uncertain about proprietary firmware. How are 
proprietary firmware files licensed?

Assuming that all closed-source drivers *and* firmware fall in the 
"encumbered" category, is there a way to prevent FreeBSD from loading 
*any* encumbered drivers while still maintaining encumbered firmware? 
Page 19 of "Absolute FreeBSD" by Michael W. Lucas* recommends avoiding 
all proprietary drivers. Is that the standard out-of-the-box behaviour 
of FreeBSD (as it is for Fedora GNU/Linux), or must a user manually 
disable proprietary drivers during/post-installation?

I would like to avoid proprietary drivers but am uncertain about how to 
do so. In Fedora GNU/Linux I simply don't enable the closed-source 
driver repositories.

* An excellent book, by the way. If you're reading this, Mr. Lucas, hi!

-- 
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