All elements of the Pascal language are explained in syntax diagrams. Syntax diagrams are like flow charts. Reading a syntax diagram means getting from the left side to the right side, following the arrows. When the right side of a syntax diagram is reached, and it ends with a single arrow, this means the syntax diagram is continued on the next line. If the line ends on two arrows pointing to each other, then the diagram is ended.
Syntactical elements are written like this 
Keywords which must be typed exactly as in the diagram: 
When something can be repeated, there is an arrow around it: 
When there are different possibilities, they are listed in rows: 
Note, that one of the possibilities can be empty: 
This means that both the first or second possibility are optional. Of course, all these elements can
be combined and nested.