Nesting aliases are what happens when one tries to alias an alias.  This is
something you should avoid doing, because it can make the MUD unplayable
until you fix it.  The following is an explanation of the MUD's logic for
how aliases work.

//Let's change the name 'cliff' to 'eight'.
alias cliff eight
Alias cliff added.

//Then we realize that this is a terrible idea.
unalias cliff
No such alias defined.

//Oh no!  What's the problem where?
retro why can't I say cliff
Cliff {retro}: why can't I say eight

//So then we look at the 'history' command.
225 alias cliff eight
226 retro why can't I say eight
227 history

//we use the 'alias' command to check out our list of aliases, and realize
that cliff is in fact aliased.
Currently defined aliases:
cliff          : eight

This is where the an escape character comes in.  An escape character is a
character that tells the program you're working with to not process
something as an alias or similar function.

unalias \cliff
Alias removed: cliff

This removes the alias for real.

And now, an explanation of why nested aliases are very bad and somewhat
difficult to remove.

//I want to alias PROT1 to major fire resistance
alias PROT1 major fire resistance
//but then I realize I want to change PROT1 to major cold resistance
alias PROT1 major cold resistance
Alias major added.

An alias in Retro can only be one word, so when Retro sees this:
   9 alias PROT1 major fire resistance
  10 alias major fire resistance major cold resistance
  11 history

It processes your request rather differently than you might expect.

Then, later on, you want to change the prot to major electrical resistance
and get this:

alias PROT1 major electrical resistance
Alias fire added.

//Why fire?  Well, look at the history:
  14 alias fire resistance major cold resistance electrical resistance fire
resistance major cold resistance electrical resistance
  15 alias
  16 history

This means anytime you type 'fire' you spit gibberish, instead.  Here's an
example:

'can we get a fire going?  I'd do it myself, but I have major bulk
problems.

You click 'Can we get a resistance major cold resistance electrical
resistance fire resistance major cold resistance electrical resistance
going?
I'd do it myself, but I have fire resistance major cold resistance bulk
problems.'

See also: alias, unalias, command