VALD Version 3.0 PRESELECT Version 3.3

1. Functionality

This program fulfills three functions: it (1) reads control
parameters via standard input, (2) opens and reads and merges
database file(s) and (3) filters the data and outputs it via
standard output.

PRESELECT3 usage can be found out using special call:
preselect3 -help

1.1. Standard input

Any text
Standard input consists of several lines. Any text in any line
following #-symbol is ignored and thus can be used as a comment.
The input has the following layout:

<starting_wavelength>,<ending_wavelength> # wavelength range
<maximum_number_of_selected_lines> # 0 = no restriction
<Ion or element or empty line>     # E.g. Fe 1 - neutral iron
                                   #      Fe   - all iron ions
                                   #           - all elements
<configuration_file>               # VALD3 configuration file
0                                  # 0 - exclude low quality data
                                   # 1 - include low quality data
a b c d e f g h i j                # Extraction flags

Flags control the out format and additional extraction filtering.
Flag meaning:
a) 0 - "short" output format (energies in eV), 1 - "long" output
   format (energies in eV), 2 - "model" output format, 3 - "short"
   format (energies in cm^-1), 4 - "long" output format (energies
   in cm^-1)
b) 1 - select only lines with known radiative damping constant
   0 - ignore this condition
c) 1 - select only lines with known Stark damping constant
   0 - ignore this condition
d) 1 - select only lines with known van der Waals damping constant
   0 - ignore this condition
e) 1 - select only lines with known Lande factors
   0 - ignore this condition
f) 1 - select only lines with known term designation
   0 - ignore this condition
g) 1 - output extended van der Waals damping constants if
       available
   0 - convert extended van der Waals damping to a standard
       constant
h) Not yet implemented
   1 - output detailed Zeeman pattern if available
   0 - do not output detailed Zeeman pattern
i) Not yet implemented
   1 - output extended Stark constants if available
   0 - do not output extended Stark constants
j) 1 - output all wavelengths in vacuum
   0 - convert wavelengths longward of 200nm to air

The default value for all the flags is 0.

1.2. VALD3 file access and unkompress3

PRESELECT uses a set of subroutines written in C to access the
VALD data files. The entry points used by PRESELECT are: UKOPEN
(opening data files), UKREAD (positioning and reading the first
data block), UKNEXT (reading the next data block) and UKCLOSE
(closing data files). Version 3 of decompression routines
includes two new features compared to the previous versions.
The first is the ability of unkompress3 to determine byte order
of the computer in the run-time. This removes the need to edit
a makefile when porting VALD to a new platform. The second
is obviously the compliance with the new record format used in
VALD3.

1.3. Output structure and formats

The output of PRESELECT is sent to standard output and consists
of 3 parts. The first line contains the name of the VALD
configuration file (without quotes). The second line is an
interpretation of the flags used for extraction using 2-symbol
tags. The format and the possible values are as follows:

1 2 3 4 5 6  <- tag number
Sf------eVAi <- default value corresponding to flag=0
MfEwZpEscmVa
Lf

Explanations:

1st tag: Sf/Mf/Lf - output is in short/model/long format
2nd tag: Ew - output contains extended van der Waals constants
3rd tag: Zp - output contains detailed Zeeman pattern
4rd tag: Es - output contains extended Stark constants
5th tag: eV/cm - output contains energies in eV/cm^-1
6th tag: Ai/Va - for lines redward of 200nm output contains
              wavelengths in air/vacuum

2. Limitations

PRESELECT has a number of configurable options set at compilation.
These point to the VALD list of species and restrict maximum sizes
of internal arrays.

2.1. Include files

An include file "VALD_home_path" set a global character variable
VALDHM the absolute path to the VALD home directory on a given
installation (no slash terminator).
An include file "VALD_species" assigns the relative path and file
name of the VALD list of species to the global character variable
VALD_SPECIES and the number of entries in the list of species is
assigned to the global integer variable VALD_sp_list_size.
Normally those two include files should be generated during make
(see the Makefile in PRESELECT directory).

2.2. Built-in restrictions

The maximum number of simultaneously open files is specified as a
global integer parameter NF. This parameter is explicitly set
inside PRESELECT (which is bad) and should instead be set at make
according to the corresponding parameter of the operating system.
Setting NF larger than the limit of the OS may result in run-time
fatal error.