'vp_files.dat' in the current directory (or a file corresponding to the the environment variable VPFFILES) can contain filenames and wavelength ranges, along the lines of filename, order#, low wavelength, high wavelength, for example:
ct92.ec 1 5950 6036
2 5793 5937
3 5644 5783
4 5505 5635
5 5370 5500
6 5245 5370
7 5120 5245
8 5005 5125
9 4893 5010
10 4786 4903
11 4685 4797
12 4590 4696
sa.ec 3 4307 4368
4 4392 4453
5 4480 4541
6 4570.4 4633
7 4665 4730
8 4765 4830.5
9 4865.8 4936
10 4976 5044
11 5090 5140
12 5140 5156.5
b92.ec 1 3738 3793
2 3801 3855
3 3867 3925
4 3934.6 3995.2
5 4004 4064.3
6 4076.9 4138.2

... this can then be used to search for regions of interest, by typing ? in response to the filename prompt from vpgti (see below), e.g.:

Filename   2 or ? (lam,n) [ct92.ec]:
?
Ion, redshift?
SiII 3.08822
File               order ion      lam0      f'    @lam   low    high
ct92.ec               6   SiII    1304.37 0.147 5332.6 5245.0 5370.0
ct92.ec               7   SiII    1260.42 1.007 5152.9 5120.0 5245.0
ct92.ec              10   SiII    1193.29 0.499 4878.4 4786.0 4903.0
ct92.ec              10   SiII    1190.42 0.250 4866.7 4786.0 4903.0
ct92.ec              17   SiII    1020.70 0.028 4172.8 4160.0 4252.0
ct92.ec              18   SiII    1020.70 0.028 4172.8 4083.0 4173.0
ct92.ec              19   SiII     989.87 0.133 4046.8 4013.0 4092.0
sa.ec                 9   SiII    1193.29 0.499 4878.4 4865.8 4936.0
sa.ec                 9   SiII    1190.42 0.250 4866.7 4865.8 4936.0
sa.ec                12   SiII    1260.42 1.007 5152.9 5140.0 5156.5
b92.ec                5   SiII     989.87 0.133 4046.8 4004.0 4064.3
Filename   2 or ? (lam,n) [ct92.ec]:
... etc.

You can take this a bit further, if you have already input parameters for
a system (say #1) at z=3.08822 for SiII (say from 1260), then a response
? (wavelength wanted) (system number) will cause a list of regions
containing that redshifted wavelength to be printed:

Filename   2 or ? (lam,n) [ct92.ec]:
? 1193 1
File               order ion      lam0      f'    @lam   low    high
ct92.ec              10   SiII    1193.29 0.499 4878.4 4786.0 4903.0
sa.ec                 9   SiII    1193.29 0.499 4878.4 4865.8 4936.0
Filename   2 or ? (lam,n) [ct92.ec]:
... etc.

This is quite useful if you are dealing with lots of lines in a messy system.