The priority of swap areas and the description in /etc/fstab..

On the RedHat7.2 IA-64 , I found the swap areas does not 
get the priority values as I wrote in /etc/fstab.
It seems the priorities are given in the order written in the file
/etc/fstab. 
This contradict the description of the online manual about swapon 
or fstab.

If I wrote the /etc/fstab about the swap areas like:
----------------------
/dev/sda5               swap swap    pri=-1    0 0
/dev/sda6               swap swap    pri=-3    0 0
/dev/sda7               swap swap    pri=-5    0 0
/dev/sda8               swap swap    pri=-7    0 0

/dev/hde5               swap swap    pri=-2    0 0
/dev/hde6               swap swap    pri=-4    0 0
/dev/hde7               swap swap    pri=-6    0 0
/dev/hde8               swap swap    pri=-8    0 0
/dev/hde9               swap swap    pri=-9    0 0
----------------------
The priority given when the OS boot up or after
	swapoff -a; swapon -a; 
is made, the actutal assigned priority is 
    sda5 > sda6 > sda7 > sda8   >    hde5 > hde6 > hde7 > hde8 > hde9
can be viewed by "swapon -s"

To make the priority of the swap ares in interleaved, which I desired,
I have to write in /etc/fstab about the swap areas as the 
intended order like:
----------------------
/dev/sda5               swap swap    pri=-1    0 0
/dev/hde5               swap swap    pri=-2    0 0
/dev/sda6               swap swap    pri=-3    0 0
/dev/hde6               swap swap    pri=-4    0 0
/dev/sda7               swap swap    pri=-5    0 0
/dev/hde7               swap swap    pri=-6    0 0
/dev/sda8               swap swap    pri=-7    0 0
/dev/hde8               swap swap    pri=-8    0 0
/dev/hde9               swap swap    pri=-9    0 0
----------------------
It seems the swap areas are added from top to bottom and 
the priorities given are higher to lower in the attached order.
The option pri= seems just been ignored.

####
The repeatition of "swapoff -a; swapon -a" makes lower 
and lower the priorities of those swap areas can be seen below:
-----------------------
% swapon -s
Filename			Type		Size	Used	Priority
/dev/sda5                       partition	2047952	64	-46
/dev/hde5                       partition	2096096	0	-47
/dev/sda6                       partition	2047952	0	-48
/dev/hde6                       partition	2096096	0	-49
/dev/sda7                       partition	2047952	0	-50
/dev/hde7                       partition	2096096	0	-51
/dev/sda8                       partition	2046928	0	-52
/dev/hde8                       partition	2096096	0	-53
/dev/hde9                       partition	2096096	0	-54
-----------------------
% swapon -s
Filename			Type		Size	Used	Priority
/dev/sda5                       partition	2047952	0	-181
/dev/hde5                       partition	2096096	0	-182
/dev/sda6                       partition	2047952	0	-183
/dev/hde6                       partition	2096096	0	-184
/dev/sda7                       partition	2047952	0	-185
/dev/hde7                       partition	2096096	0	-186
/dev/sda8                       partition	2046928	0	-187
/dev/hde8                       partition	2096096	0	-188
/dev/hde9                       partition	2096096	0	-189
-----------------------

Am I making any elemental mistake how to specify the priority 
for swap areas in /etc/fstab?

H.M.