I had run the chgiphost.bat on a Windows AS 10.1.3.0.0. The reason for this was the fact that the Windows machine was created from a Ghost image.
But after the script has been run successfully I saw that the hostname was still the same in the Application Server Control.

So I created a SR with Support. And today I received a very good answer. Normally Support gives you a statement that it does not work and that's that. But see for yourself what this friendly analyst did say:

The dcmctl setInstanceName is available from 9.0.4 onwards. This will change the instance name in the DCM Repository.
After this you may have to change the targets.xml file with the new instance name. Please note that the above command is not supported as this is not documented."

Ok, very good!
I will make sure that this guy gets an excellent review.

However there is now cmctl in 10.1.3.0.0 and also no targets.xml :-(

But actually the idea was clear to me.

I went to have a look at the opmn.xml file.

When I changed
< id="as1013.OLDHOSTNAME.mymachine.local" name="as1013.OLDHOSTNAME.mymachine.local">

to

< id="as1013.NEWHOSTNAME.mymachine.local" name="as1013.NEWHOSTNAME.mymachine.local">

everything worked as I expected it to do.