When you need to use symbols defined in other modules you must import them first. You import symbols using the .IMPORT directive.
IMPORT
symbol [::
type] [,
symbol
[::
type]]...
EXTERN
symbol [::
type] [,
symbol
[::
type]]...
XREF
symbol [::
type] [,
symbol [::
type]]...
When importing a symbol you can also define its type. This type information is used by the assembler whenever you reference the imported symbol and acts just like a symbol declared locally within the module. If you don't define a type for the imported variable, no type information is available to the assembler. If you subsequently use such a variable where type information is required, the assembler will report an error.
IMPORT CLA::BYTE, La::WORD IMPORT APDUData::BYTE[256] IMPORT _myVar
The above imports CLA as a byte, La as a 32-bit word, APDUData as an array of 256 bytes, and _myVar without type information.