Relationship between PL and Correctness (4) ° Maintainability Locality--possible to isolate changes Self-documenting Programming decisions should be recorded in program, independent of external documentation Good comment convention freedom to choose meaningfu variable names etc User-defined types and named constants e.g., type direction=(north, south, east, west) Explicit interfaces Should cater to construction of hierarchies of modulesCopyright Nancy Leveson, Sept. 1999 Relationship between PL and Correctness (4) Maintainability Locality -- possible to isolate changes. Self-documenting Programming decisions should be recorded in program, independent of external documentation. Good comment convention, freedom to choose meaningful variable names, etc. User-defined types and named constants e.g., type direction=(north, south, east, west) Explicit interfaces Should cater to construction of hierarchies of modules � c