the program or are standard ("pll,'declared") entities. Pascal defines a fixed set of operators, each of \\ hich can be regarded as describing a mapping from the operand typ."s into the result type. The set of operators is divided into four gn 'ups. 

1. Arithmetic operators al'e addition, subtraction, sIgn inversion, multiplication, division, and modulus. 

2. Boolean operators ar,,' negation, union (or), and conjunction (and). 

3. Set operators are union, intersection, and set difference. 

4. Relational operators are I;'quality, inequality, ordering, set membership, and set inclusion. The result type of relational operators is B ,olean. 

The procedure statement cau ',es the execution of the designated procedure (see below). Assignm( lit and procedure statements are the components, or "building block<' of structured statements, which specify sequential, selective, llr repeated execution of their components. Sequential execution of statements is specified by the compound statement, conditional or selective execution by the if and case statements, and repeated exe'l'ution by the repeat, while, andjor statements. The if statement serve~ to make the execution of a statement dependent on the value of a Boolean expression, and the case statement allows the selection among many ,tatements according to the value of an ordinal expression. The for ,tatement is used to execute the component statement while each If a succession of ordinal values is assigned to a so-called control variable. The repeat and while statements are used otherwise. 

In addition, Pascal provides a, I If I I statement, which indicates that execution is to continue at anothel place in the program; that place is marked by a label, which must be .lcl'lared. 

Statements along with declal :11 Ions of labels, constants, types, variables, procedures, and functiOJ. ,Ire collected together into blocks. The labels, constants, variables, types, procedures and functions declared in a block may be referil,'d to only within that block, and therefore are called local to tl It' block. Their identifiers have significance only within the progralll text that constitutes the block and that is called the scope of these ick'ntifiers. Blocks are the basis for 

