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A model so based, the contour model, is introduced by illustrating the execution of an ALGOL 60 program in terms of the model. The model is informally specified and some of its major features are pointed out. A companion paper by D. M. Berry shows that semantically powerful languages can be directly implemented in terms of the model.<\/jats:p>","DOI":"10.1145\/1115880.1115883","type":"journal-article","created":{"date-parts":[[2006,5,8]],"date-time":"2006-05-08T22:51:53Z","timestamp":1147128713000},"page":"55-82","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":78,"title":["The contour model of block structured processes"],"prefix":"10.1145","volume":"6","author":[{"given":"John B.","family":"Johnston","sequence":"first","affiliation":[{"name":"General Electric Corporate Research and Development Schenectady, New York"}]}],"member":"320","published-online":{"date-parts":[[1971,2]]},"reference":[{"key":"e_1_2_1_1_1","first-page":"134","volume":"6","author":"Barron D. W.","year":"1963","unstructured":"B1. Barron , D. W. , The Main Features of CPL. Comp. J. 6 ( 1963 ), 134 -- 143 . B1. Barron, D. W. et al., The Main Features of CPL. Comp. 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