!TITLE APPENDIX B: Implementation Notes
!KEY

This section will be expanded shortly.
!<EMAS IMP80
!KEY
!<Compile-time errors
!KEY
  The IMP compiler can generate any of the following messages while
  compiling a program.  The following points should be noted:

   * The symbols '#' and '##' appearing in any of the messages below are
     replaced by appropriate integer values when the message is output
     by the compiler.

   * The symbols '&' and '&&' appearing in any of the messages below are
     replaced by appropriate names (of program variables, routines,
     switches, etc.) when the message is output by the compiler.

   * Messages numbered 1-100 relate to standard compile-time errors.
     Messages numbered 101-200 relate to various compile-time limits
     (compiler table sizes, etc.) being exceeded.  Messages with numbers
     greater than 200 are warnings - they do not in themselves indicate
     an error in the program being compiled.
!PAGE
        1  %repeat is not required
        2  Label & has already been set in this block
        4  & is not a Switch name at current textual level
        5  Switch name & in expression or assignment
        6  Switch label &(#) set a second time
        7  Name & has already been declared
        8  Routine or fn & has more parameters than specified
        9  Parameter # of & differs in type from specification
       10  Routine or fn & has fewer parameters than specified
       11  Label & referenced at line # has not been set
       12  %cycle at line # has two control clauses
       13  %repeat for %cycle at line # is missing
       14  %end is not required
       15  # %ends are missing
       16  Name & has not been declared
       17  Name & does not require parameters or subscripts
       18  # too few parameters provided for &
       19  # too many parameters provided for &
       20  # too few subscripts provided for array &
       21  # too many subscripts provided for array &
!PAGE
       22  Actual parameter # of & conflicts with specification
       23  Routine name & in an expression
       24  Integer operator has real operands
       25  Real expression in integer context
       26  # is not a valid %event number
       27  & is not a routine name
       28  Routine or fn & has specification but no body
       29  %function name & not in expression
       30  %return outwith routine body
       31  %result outwith fn or map body
       34  Too many textual levels
       37  Array & has too many dimensions
       38  Array & has upper bound # less than lower bound
       39  Size of Array & is more than X'FFFFFF' bytes
       40  Declaration is not at head of block
       41  Constant cannot be evaluated at compile time
       42  # is an invalid repetition factor
       43  %constant name & not in expression
       44  Invalid constant initialising & after # items
       45  Array initialising items expected ## items given #
!PAGE
       46  Invalid %external, %extrinsic or variable %spec
       47  %else already given at line #
       48  %else invalid after %on %event
       49  Attempt to initialise %extrinsic or %format &
       50  Subscript of # is outwith the bounds of &
       51  %finish is not required
       52  %repeat instead of %finish for %start at line #
       53  %finish for %start at line # is missing
       54  %exit outwith %cycle %repeat body
       55  %continue outwith %cycle %repeat body
       56  %externalroutine & at wrong textual level
       57  Executable statement found at textual level zero
       58  Program among external routines
       59  %finish instead of %repeat for %cycle at line #
       61  Name & has already been used in this %format
       62  & is not a %record or %record %format name
       63  %record length is greater than # bytes
       64  Name & requires a subname in this context
       65  Subname & is not in the %record %format
       66  Expression assigned to record &
!PAGE
       67  Records && and & have different formats
       69  Subname && is attached to & which is not of type %record
       70  String declaration has invalid max length of #
       71  & is not a string variable
       72  Arithmetic operator in a string expression
       73  Arithmetic constant in a string-expression
       74  Resolution is not the correct format
       75  String expression contains a sub expression
       76  String variable & in arithmetic expression
       77  String constant in arithmetic expression
       78  String operator '.' in arithmetic expression
       80  Pointer variable & compared with expression
       81  Pointer variable & equivalenced to expression
       82  & is not a pointer name
       83  && and & are not equivalent in type
       86  Global pointer && equivalenced to local &
       87  %format name & use in expression
       90  Untyped name & used in expression
       91  %for control variable & not integer
       92  %for clause has zero step
!PAGE
       93  %for clause has noninteger number of traverses
       95  Name & not valid in assembler
       96  Operand # not valid in assembler
       97  Assembler construction not valid
      101  Source line has too many continuations
      102  Workfile of # Kbytes is too small
      103  Dictionary completely full
      104  Dictionary completely full
      105  Too many textual levels
      106  String constant too long
      107  Compiler tables are completely full
      108  Condition too complicated
      109  Compiler inconsistent
      201  Long integers are inefficient as subscripts
      202  Name & not used
      203  Label & not used
      204  Global %for control variable &
      205  Name & not addressable
      206  Semicolon in comment text
      255  Unexpected fault - consult ERCC Advisory Service
!>
!<Miscellaneous notes
!KEY
  <To follow.>
!>
!>
!<IMP77
!KEY

  To follow
!>