Sun 4.0.3 block device weirdness

[Sam McCall]

Scenario:  a sun 3/260 running SunOS 4.0.3.  The following script
shows some behavior I don't understand.  I'd love to know why it's
doing what it's doing, and why.  (I also hope that it's a wizardly
enough question to appease Randal (-;).

	Script started on Thu Aug  9 00:08:37 1990
	bullwinkle% cd /tmp
	bullwinkle% ls -aCF
	./	../	.getwd
	bullwinkle% df .
	Filesystem            kbytes    used   avail capacity  Mounted on
	/dev/xd0a              15720    9877    4271    70%    /
	bullwinkle% cp /.login xyzzy
	bullwinkle% ls -aCF
	./	../	.getwd	xyzzy
	bullwinkle% ls -CFainsl xyzzy
	   293    1 -rw-r--r--  1 ccsam         751 Aug  9 00:09 xyzzy
	bullwinkle% ncheck -i 293 /dev/xd0a
	/dev/xd0a:
	293  	/tmp/.getwd
	bullwinkle% ncheck -i 293 /dev/rxd0a
	/dev/rxd0a:
	293  	/tmp/xyzzy
	bullwinkle% ncheck -i 293 /dev/xd0a
	/dev/xd0a:
	293  	/tmp/.getwd
	bullwinkle%
	script done on Thu Aug  9 00:10:05 1990