TOPS-20 PASCAL Language Manual - Bitsavers

EXPRESSIONS
Similarly, local identifiers declared in Level 1B are accessible to
LevellB, Level ~~B, and Level2C, but not to Level lA, Level ?A,
Level-3A, or the nain program.
In general, once you define an identifier, it retRins its meaning
within the block containing its declaration. You can, however,
redefine an identifier in a subprogram at a lower level. If you do
so, the identifier assumes its new meaning only within the scope of
the redefining block. Outside this block, the identifier keeps its
original meRning. For example, B is declared at program level and
redefined in Level 2C. Within the scope of Level 2C, B denotes a
Boolean variable. ·Everywhere else in the program,-however, B denotes
Rn integer.
The identifiers accessible to each routine in Figure 3-1 are listed
below.
Routine
-----
Variables
Main p:rog ram A, B ( :i. n t f::' ~.:.! f~ T' )
l..evf~ll .... :LA
A, B ( i ntt~~tp T') , r _. 1:1
L..f?vf?l .... :?A A, B ( i nte5.!e T') y C , , Dy E
Level.. .. 3A Ay B ( i ntf.~~J(·? T' ) , C, [I, [y r
..
LeVE' 1 __ :L B
A, B ( :i. ntf.~~~e T' ) , G
L f? V t~ 1 .. _ 2 B A, B ( integer) , (3y H
Level .... 2C A, B (Boolean) , ,J
3-9