Actually M-X does do 
On 1 May 2015, at 18:38, Johnny Billquist <bqt at softjar.se> wrote:
  On 2015-05-01 08:37, Sampsa Laine wrote:
  Just out of of interest, how do you do ESC-X
(Command completion with tab) and ESC-% (Query search/replace) on MicroEMACS? 
 
 M-X is not "command completion", but extended commands, and MicroEMACS do not
have them.
 Nor do I remember any query replace function. Like I said, MicroEMACS has its
limitations.
 
 	Johnny
  
I wasn't complaining, just asking what the equivalent commands if any are..
M-X ?  gives a list of what I assume are all commands (see screencap at
http://sampsa.com/ue.png)
M-X query-replace-string in MicroEMACS actually works, it's just not bound to M-%.
Sampsa