public CRPosting AppendPosting(InstrumentType instrumentType, IFinancialAccount account, decimal amount) {
      CRPosting posting = new CRPosting(this, instrumentType, account, amount);
      this.Postings.Add(posting);

      return posting;
    }
 public bool RemovePosting(CRPosting posting) {
   return this.Postings.Remove(posting);
 }
    public CRPosting AppendPosting(InstrumentType instrumentType, CRDocument document, decimal amount) {
      CRPosting posting = new CRPosting(this, instrumentType, document, amount);
      this.Postings.Add(posting);

      return posting;
    }