Identifier   define_yaaar

 Purpose      Define a YAAAR IDL structure

 Synopsis     YAAAR = define_yaaar([, header=header] [, length=length]
                               [, data=data])

 Arguments    Name   I/O Type:     Description:
              -------------------------------------------------
              header  I  string    Header definition 
              length  I  integer   Size of the structure [default=0]
              data    I  struc     Data structure

 Returns      YAAAR structure

 Description  Definition of the YAAAR structure, following the complete 
              AAR structure of define_yaaar.pro.
              This routine creates an YAAAR structure with pre-defined 
              YAAAR header of makeyaaarhead.pro and an empty data structure 
              of specified or default length.

 Comment      See also define_aar.pro (IA)

 Dependencies CALLS: sap_keyword_set, makeyaaarhead

              CALLED FROM: GUI, IA, ascii2yaaar

 Example      YAAAR = define_yaaar(header=hdr, length=200)

 Category     ISAP

 Filename     define_yaaar.pro

 Author       P. Morris
              p.morris@sron.ruu.nl

 Version      1.1

 History      1.0  10-25-95 PM creation of routine, only 4 data tags: 
                               wave,flux,stdev,flag
              1.1  12-03-95 PM added all remaining AAR data tags