Quote: a Sketchpad type is a ring of objects under a generic heading; the generic heading defines the type and its subroutines

Quotation Skeleton

In the [Sketchpad] data storage structure the separation … ring under a generic heading. The generic heading … things. Thus the data storage structure itself contains … Addition of new types of things to the … 20 registers) and the writing of appropriate subroutines … new constraints, or difficult to write, as for … ability to the system. Without a generic structure … element.   Google-1   Google-2

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Additional Titles

Quote: constructing a new type in Sketchpad is a finite, well-defined task; construct a generic block of 20 registers and the corresponding subroutines

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