In current higher level languages arrays are parallelepiped in N dimensions, each dimension having an index range from a lower limit to an upper limit (both must be integers), the increment between valid index values being one.By removing the r e s t r i ction of limits and increments to be integers or unity, a homogenously addressed sections or t e a s of an array is defined. Co~.~ining several of these regions each with its own limits and increments but with com~non addressin~forms an array with varying data density.These new arrays are referred to as Varying Density Arrays (VDA).All data elements of a given region are restricted to a single format and structure.The element structure and format of one region in no way restricts elements in other regions. This generalization permits uniform addressing of conventional arrays, VDAs and PL/I or COBOL structures. This paper discusses (i) the concept of a VDA, (2) extensions to PL/I declarations to allow the definition of VDAs, (3) gives examples in PL/I and APL and discusses operations of VDAS and their subarrays.The paper touches on, but does not discuss, mappings to physical storage.

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