150  Pascal Report  Examples of identifiers (six di.  lillct  spellings):  FirstPlace  Elizabeth  ord  John  I'  r  ocedureOrFunctionDeclaration  "rocedureOrFunctionHeading  A specific identifier spellmg is  introduced by a declaration or  definition to have a specific meaning, and that identifier spelling cannot  have any other meaning within a region of the program text that is called  the  scope  of that declaration or definition (see Section 10).  Numbers are expressed using the usual decimal notation. Unsigned  integers  and  unsigned  reals  are,  respectively,  constants  of the  predefined types Integer and R,:al (see Section 6.1.2). The letter  "e"  preceding the scale factor in an unsigned real means "times 1 0 to the  power." The maximum value th.iI an  Unsignedlntegermay  represent is  the implementation-defined va lie of the predefined constant  Maxint.  UnsignedNumber  =  Unsigned/III,' ,:a  )  UnsignedReal .  Unsigned/nteger  =  DigitSeque/l("  UnsignedReal  =  DigitSequence  .. "  DigitSequence  [" e"  ScaleF actor]  ) DigitSequi'lIc('  "e"  ScaleFactor.  ScaleFactor  =  [Sign] DigitSeqUt  IICC .  Sign  =  "+"  ) "-" .  DigitSequence  =  Digit  {  Digit} .  Examples of unsigned integers:  1  100  0010(  Examples of unsigned reals:  0.1  O.leO  1E2  The signed numbers are the fom  I  that is acceptable for numeric input  from textfiles (see Section 12).  SignedNumber  =  Signed/nteger)  S  1.:II('dRcul.  Signed/nteger  =  [Sign] Unsigned.'  '111'L:('1' .  SignedReal  =  [Sign] UnsignedRc,iI.  Character strings are sequences of string elements enclosed in  apostrophes. A string element represents an implementation-defined  value of the predefined type Chal . and consists either of two adjacent  apostrophes or of any other implementation-defined character. Two 