st: How to list all the observation meeting the conditions which are the former results?

[Grace Jessie <gracejessie@hotmail.com>]

Dear statalists,
How to list all the observation meeting the conditions which are the former results?
For example,
. clear
. input x y z
             x          y          z
  1. 1 2 8
  2. 1 2 2
  3. 2 3 4
  4. 2 3 9
  5. 2 4 8
  6. end
. l
     +-----------+
     | x   y   z |
     |-----------|
  1. | 1   2   8 |
  2. | 1   2   2 |
  3. | 2   3   4 |
  4. | 2   3   9 |
  5. | 2   4   8 |
     +-----------+
. l if z<5
     +-----------+
     | x   y   z |
     |-----------|
  2. | 1   2   2 |
  3. | 2   3   4 |
     +-----------+
Now I want to list all the observations for each x and y combination in the former results,i.e.,(x==1 & y==2) | (x==2 | y==3).
I know I can type "l if (x==1 & y==2) | (x==2 | y==3)".
However, typing one by one is troublesome if the number of the combinations for the former results is large.
I know -levelsof- can solve the problem if not the combination but just one variable.
Is there a way like -levelsof- ?
Thank you!
Grace
  		 	   		  
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