Net operating losses sustained by real estate investment trusts, which qualify as such under section 856 and which are taxable under section 857 of the Internal Revenue Code, may not be carried back as net operating loss deductions for the purposes of article 9-A. However, a net operating loss carry forward is allowed under article 9-A which is presumably the same as that which is allowed for Federal income tax purposes, subject to the limitations explained in section 3-8.2 of this Subpart.