NB: column filters work on tables only. Regions work on tables and images.

1. Please show how to use column and regions filters
   1. Filter events through a circular region using physical pixels

      fundisp foo.fits'[circle(512,512,.5)]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  512   6   7     79493997.45854475  578  574
       512  512   8   9     79494575.58943175  579  573
       512  512   5   6     79493631.03866175  578  575
       512  512   5   5     79493290.86521725  578  575
       512  512   8   9     79493432.00990875  579  573
      

   2. Filter events through a circular region, for a single value of pha

      fundisp foo.fits'[circle 512 512 .5 && pha==5]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  512   5   6     79493631.03866175  578  575
       512  512   5   5     79493290.86521725  578  575
      

   3. Filter events through a circular region, including a range of pha values

      fundisp foo.fits'[circle(512,512,.5)&&pha=5:6]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  512   6   7     79493997.45854475  578  574
       512  512   5   6     79493631.03866175  578  575
       512  512   5   5     79493290.86521725  578  575
      

   4. Filter events through a circular region, excluding a range of pha values

      fundisp foo.fits'[circle(512,512,.5)&&\!pha=5:6]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  512   8   9     79494575.58943175  579  573
       512  512   8   9     79493432.00990875  579  573
      

   5. Filter events through two circular regions

      fundisp foo.fits'[circle(512,512,.5); circle 500 500 .1]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       500  500   5   5     79493733.05197725  600  577
       500  500   9   9     79488217.13936825  600  576
       500  500   2   2     79487590.99904275  599  581
       512  512   6   7     79493997.45854475  578  574
       512  512   8   9     79494575.58943175  579  573
       512  512   5   6     79493631.03866175  578  575
       512  512   5   5     79493290.86521725  578  575
       512  512   8   9     79493432.00990875  579  573
      

   6. Filter events through a circular region, selecting a single time value

      fundisp foo.fits'[circle(512,512,.5)&&time==79493631.03866175]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  512   5   6     79493631.03866175  578  575
      

   7. Filter events through a circular region, selecting a single time value (but using feq to avoid possible precision problems)

      fundisp foo.fits'[circle(512,512,.5)&&feq(time,79493631.03866175)]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  512   5   6     79493631.03866175  578  575
      

   8. Filter events through a circular region, while excluding an inner circle

      fundisp foo.fits'[circle(512,512,1);-cir 512 512 .5]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  511   9   9     79492909.11908525  580  572
       512  511   6   7     79492607.35239075  580  573
       512  511   6   7     79493574.08603576  580  573
       512  511   7   8     79488537.75487424  579  572
       511  512   5   5     79488781.64644176  579  576
       511  512   5   6     79492586.05470325  579  576
       511  512  10  10     79494397.55842775  580  574
       511  512   1   2     79493697.87522624  577  582
       511  512   6   7     79493997.75123225  579  575
       511  512  10  11     79487417.67703976  579  574
       513  512   6   6     79493306.47509325  578  573
       513  512   8   8     79487909.39373726  578  572
       512  513   4   4     79487403.52010125  576  577
       512  513   8   9     79492536.31151475  577  574
       512  513  10  10     79492589.71195325  578  574
       512  513   5   5     79488335.19512025  576  575
       512  513   8   8     79493661.25728776  578  574
       512  513   8   9     79487914.98186225  577  574
       512  513   5   5     79487392.91247626  577  576
       512  513   4   4     79492808.24789475  577  576
       512  513   7   8     79493236.90765475  577  574
       512  513   6   7     79493667.65710025  578  574
      

   9. Filter events through a circular region for a range of pha, while excluding an inner circle

      fundisp foo.fits'[circle(512,512,1)&&pha=6:7;-cir 512 512 .5]'
       
         X    Y PHA  PI                  TIME   DX   DY
      ---- ---- --- --- --------------------- ---- ----
       512  511   6   7     79492607.35239075  580  573
       512  511   6   7     79493574.08603576  580  573
       512  511   7   8     79488537.75487424  579  572
       511  512   6   7     79493997.75123225  579  575
       513  512   6   6     79493306.47509325  578  573
       512  513   7   8     79493236.90765475  577  574
       512  513   6   7     79493667.65710025  578  574
      

   10. Filter events through a circular region for ranges of pha and pi, while excluding an inner circle

       fundisp foo.fits'[circle(512,512,1)&&pha=5:7 && pi=6:8;-cir 512 512 .5]'
        
          X    Y PHA  PI                  TIME   DX   DY
       ---- ---- --- --- --------------------- ---- ----
        512  511   6   7     79492607.35239075  580  573
        512  511   6   7     79493574.08603576  580  573
        512  511   7   8     79488537.75487424  579  572
        511  512   5   6     79492586.05470325  579  576
        511  512   6   7     79493997.75123225  579  575
        513  512   6   6     79493306.47509325  578  573
        512  513   7   8     79493236.90765475  577  574
        512  513   6   7     79493667.65710025  578  574
       

   11. Filter events through a circular region in fk5 coords (degrees)

       fundisp foo.fits'[fk5;circle(345.25391,58.879774,3.9999997")]'
        
          X    Y PHA  PI                  TIME   DX   DY
       ---- ---- --- --- --------------------- ---- ----
        512  512   6   7     79493997.45854475  578  574
        512  512   8   9     79494575.58943175  579  573
        512  512   5   6     79493631.03866175  578  575
        512  512   5   5     79493290.86521725  578  575
        512  512   8   9     79493432.00990875  579  573
       

   12. Filter events through a circular region retrieved from ds9

       cat foo.reg
       # Region file format: DS9 version 4.0
       # Filename: foo.fits'[EVENTS]'
       global color=green font="helvetica 10 normal" select=1 highlite=1 edit=1 move=1 delete=1 include=1 fixed=0 source
       fk5
       circle(345.25391,58.879774,3.9999997")
       
       fundisp foo.fits'[@foo.reg]'
        
          X    Y PHA  PI                  TIME   DX   DY
       ---- ---- --- --- --------------------- ---- ----
        512  512   6   7     79493997.45854475  578  574
        512  512   8   9     79494575.58943175  579  573
        512  512   5   6     79493631.03866175  578  575
        512  512   5   5     79493290.86521725  578  575
        512  512   8   9     79493432.00990875  579  573