Trailing parameters should be treated the same as other parameters.

[aatxe]

As pointed out on the IRCv3 channel, the library shouldn’t present a difference between trailing and middle parameters to users. This mistake has persisted for a long time, but correcting it should actually simplify a lot of code (though the change will be breaking).

After extracting the parameter list, all parameters are equal whether matched by <middle> or <trailing>.

Source: https://tools.ietf.org/html/rfc2812#section-2.3.1