#### 9.15.3 Syntax

The assembler syntax closely follows the HPPA instruction set reference manual; assembler directives and general syntax closely follow the HPPA assembly language reference manual, with a few noteworthy differences.

First, a colon may immediately follow a label definition. This is simply for compatibility with how most assembly language programmers write code.

Some obscure expression parsing problems may affect hand written code which uses the `spop` instructions, or code which makes significant use of the `!` line separator.

`as` is much less forgiving about missing arguments and other similar oversights than the HP assembler. `as` notifies you of missing arguments as syntax errors; this is regarded as a feature, not a bug.

Finally, `as` allows you to use an external symbol without explicitly importing the symbol. Warning: in the future this will be an error for HPPA targets.

Special characters for HPPA targets include:

‘`;`’ is the line comment character.

‘`!`’ can be used instead of a newline to separate statements.

Since ‘`$`’ has no special meaning, you may use it in symbol names.