Upright units are also made with combinations of drawers for different purposes. For a small business, an assortment of files for different purposes is frequently desirable. An entire section filled with files of one kind may not be needed, but a combination section offers a solution. The combination illustrated in Fig. 30 contains one cupboard, six shallow storage blanks, two double card-index drawers, and three document files. A vertical file drawer can be substituted for the cupboard unit. If vouchers, or other folded documents are to be filed, the document drawers shown in the combination unit can be used, or provision can be made for filing these papers in the vertical file. The vertical file drawer is divided lengthwise by partitions into compartments of the same width as the document file. Each compartment is equipped with a follower block and countersunk rod for holding guides. [Illustration: Fig. 30. Combination Cabinet _Browne-Morse Co._] Where a large number of folded documents are to be filed, as in the office of a corporation using a voucher system, this file is much more convenient than the old style. An old-style document file has a limited filing capacity, and must be taken from the cabinet for consultation. A vertical file drawer, legal size, provides three compartments, each 24" in length. This gives an actual filing capacity of six feet in a single drawer. An upright section, equipped for document filing, is shown in Fig. 31. If an entire section is not needed for this purpose, one drawer can be equipped for document filing, and the others used for correspondence. [Illustration: Fig. 31. Upright Cabinet for Documents _Library Bureau_] A style of construction designed to combine the expansion idea with variety is known as the _inter-inter cabinet_. This cabinet consists primarily of an outer cabinet or shell of standard height, depth, and width. This shell is divided into compartments of standard height into which the filing devices are fitted. The various filing devices are arranged in skeleton units of standard dimensions, made interchangeable so that any desired combination can be produced. Fig. 32 shows an outside cabinet, card index, and vertical file units, which fit the openings in the cabinet. [Illustration: OUTSIDE CABINET] [Illustration: Fig. 32. Inter-Inter Construction _Macey Co._] This construction enables the user to make a combination of small units of various kinds to suit present requirements, all housed in a single case in a compact form. Provision for future expansion is unnecessary, since an additional outside cabinet can be added at any time, and the units rearranged at will to conform with changes in the system. An inter-inter cabinet shown in Fig. 33 suggests the variety of devices that can be accommodated in a single shell. This cabinet contains vertical file, card index, legal blank drawers, and document files.