ADAS Subroutine xxprs3

       subroutine xxprs3( string , ia_dim     , iz0   , iz    , 
     &                    ia     , ia_vlnce 
     &                  )
c-----------------------------------------------------------------------
c
c  ****************** fortran77 subroutine: xxprs3 *********************
c
c  purpose:  To analyse a configuration character string in Standard 
c            form into a  integer array of occupation numbers in the 
c            normal collating order.
c
c            unified version of bbprs3 & g5prs3 and a replacement for
c            these subroutines

c  calling program: various
c
c  notes:   1. the normal collating order is 1s,2s,2p,3s,3p,3d etc.
c           2. a strategy for deciding the occupancy of unspecified
c              inner shells is implemented using the nuclear and ion
c              charge.  The strategy may be switched off.
c           3. opens a central ADAS adf00 file for an element on 
c              unit 10. 
c
c
c  subroutine:
c
c  input : (c*(*))string   =  string to be parsed
c  input : (i*4)  ia_dim   =  dimensionality of occupancy vector ia
c  input : (i*4)  iz0      =  nuclear charge 
c  input : (i*4)  iz       =  ion charge 
c
c  output: (i*4)  ia()     =  set of occupation numbers in standard
c                             collating list order
c  output: (i*4)  ia_vlnce =  outer occupied shell index in collating
c                             list
c
c  routines:
c          routine    source    brief description
c          -------------------------------------------------------------
c          i4unit     adas      fetch unit number for output of messages
c          xxopen     adas      inquire & open a data file on a unit 
c          xxword     adas      parses a string into separate words
c          xxrmve     adas      removes occurrences of a char. in string
c          xxcase     adas      changes a string to upper or lower case
c          xxslen     adas      finds the length of a string excluding
c                               leading and trailing blanks
c          xfesym     adas      fetch the chemical symbol of an element
c
c
c author:  H. P. Summers
c          JA7.08, University of Strathclyde
c          Tel: 0141-548-4196 4941
c
c date:    16/12/02
c
c update:
c
c-----------------------------------------------------------------------
      CHARACTER*(*)       STRING
      INTEGER             IA(IA_DIM),  IA_DIM,      IA_VLNCE,    IZ
      INTEGER             IZ0