Unit

The unit is the mechanism for modularization of a Pascal program; it is written and compiled separately from the main program.

Syntax Diagram

BNF

<unit>

::= <unit-heading> ';' <interface-section> ';' <implemntation-section> ';' <initialization-section> '.'

<unit-heading>

::= 'UNIT' <unit-name>

<unit-name>

::= <identifier>

<interface-section>

::= 'INTERFACE' <interface-declaration-list>

<interface-declaration>

::= <constant-section>

::= <function-declaration>

::= <procedure-declaration>

::= <type-section>

::= <variable-section>

<implementation-section>

::= 'IMPLEMENTATION' <implementation-declaration-list>

<implementation-declaration>

::= <constant-section>

::= <function-definition>

::= <label-section>

::= <procedure-definition>

::= <type-section>

::= <variable-section>

<initialization-section>

::= 'END'

::= <compound-statement>

EBNF

<unit>

::= <unit-heading> ';' <interface-section> ';' <implemntation-section> ';' <initialization-section> '.'

<unit-heading>

::= 'UNIT' <unit-name>

<unit-name>

::= <identifier>

<interface-section>

::= 'INTERFACE' <interface-declaration> *

<interface-declaration>

::= <constant-section>
|  <function-declaration>
|  <procedure-declaration>
|  <type-section>
|  <variable-section>

<implementation-section>

::= 'IMPLEMENTATION' <implementation-declaration> *

<implementation-declaration>

::= <constant-declaration-section>
|  <function-definition>
|  <label-declaration-section>
|  <procedure-definition>
|  <type-declaration-section>
|  <variable-declaration-section>

<initialization-section>

::= <compound-statement>
|  'END'

• The unit is the mechanism for modularizing a Pascal programs. 
• Units are separately compiled.
• Units can provide functions, procedures, types, constants, and variables which can be used by programs.

• The unit is a Borland extension to standard Pascal.