ars_SetField(ctrl, schema, fieldId, fieldHash)fieldHash before calling this routine.
      schema is the name of the schema containing the field.
      
fieldId is numeric id of the field.
      
fieldHash is an 
      Field Attributes hash. 
      
Example:
This example increases the content length of a character field. It also specifies write permission for group 505 and read permission for group 506.
      ($fd = ars_GetField($c, "Schema", $fieldId )) ||
	    die $ars_errstr;
	
      $fd->{limit}{maxLength} += 30;
      ars_SetField( $c, "Schema", $fieldId, {
        permissions => { 505 => "change", 506 => "view" },
        limit       => $fd->{limit},
      } ) || die $ars_errstr;
      
This function was introduced in version 1.90 of ARSperl