- Page 506, Section 2, first paragraph in the middle,
    the following sentence to define set X is missing:
    "The set of program variables that occur in program operations from Ops is denoted by X."
- Page 506, Section 2.1, 9th line from bottom: 
    "preorder" -> "partial order"
- Page 507, Section 2.1, in item 4 about termination check: 
    "preorder" -> "partial order"