Dbf Class structure:
~~~~~~~~~~~~~~~~~~~~
create class Dbf
  export:
  var lNew         //false
  var Data         //{}
  method New=DbfNew                 //o:New() --> self
  method Password=DbfPassword       //o:Password() --> true
  method Init=DbfInit               //o:Init() --> true
  method Create=DbfCreate           //o:Create() --> true
  method Open=DbfOpen               //o:Open() --> true
  method ReIndex=DbfReIndex         //o:ReIndex(lContinue) --> true/false
  method Pack=DbfPack               //o:Pack(lContinue) --> true/false
  method Zap=DbfZap                 //o:Zap(lContinue) --> true/false
  method AddDbf=DbfAddDbf           //o:AddDbf(cFile) --> true
  method AddField=DbfAddField       //o:AddField(cName,cType,nLen,nDec) --> true
  method AddNtx=DbfAddNtx           //o:AddNtx(cName,cFile,cKey,lUnique) --> true
  method AddRelation=DbfAddRelation //o:AddRelation(xKey,cAlias,nOrder) --> true
  method Picture=DbfPicture         //o:Picture(cPict) --> true
  method Range=DbfRange             //o:Range(nLo,nHi) --> true
  method When=DbfWhen               //o:When(bWhen) --> true
  method Valid=DbfValid_            //o:Valid(bValid) --> true
  method ChValid=DbfChValid         //o:ChValid(bValid) --> true
  method Save=DbfSave               //o:Save(cPath) --> true/false
  method Load=DbfLoad               //o:Load(cPath) --> do_nothing
  method Done=DbfDone               //o:Done() --> true
  endclass