(1) In this section -
"property investment scheme" means any scheme or arrangement made for the purpose, or having the effect, of providing facilities, whether promoted by means of public advertisement or otherwise, for the public or a section of the public to share, either directly or indirectly and whether as beneficiaries under a trust or by any other means, in income or gains arising or deriving from the acquisition, holding or disposal of, or of an interest in, a building or structure or a part of a building or structure, but does not include a scheme or arrangement as respects which the Revenue Commissioners or, on appeal, the Appeal Commissioners, having regard to such information as may be produced to them, are of the opinion that -
(a) the manner in which persons share in the income or gains, and
(b) the number of persons who so share,
are in accordance with a practice which commonly prevailed in the State during the period of 5 years ending immediately before the 30th day of
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