Uses standard 6502 syntax
Supports 65C02 instruction set
Denote hex literals with '&' or '$'
Denote binary literals with '%'
Multiple statement lines, statements separated by colons
Define labels with .label, like BBC BASIC
Assign variables with addr=&70, like BBC BASIC
Add bytes, words and strings with EQUB, EQUW, EQUD and EQUS - as an extension to BBC BASIC, these can take a comma-separated list
FOR...NEXT
IF...ELIF...ELSE...ENDIF
Supports all of the BBC BASIC functions and operators in expressions, e.g. SIN, COS, SQR, DIV, MOD, etc etc
Save object code to a disc image or to a standalone file
INCLUDE "file" to include another source file
Ability to set a guard on a memory address so it will warn you if it is assembled over
Use braces { } to enclose blocks of code so that all labels and variables defined within will be local to that block.
INCBIN command to include a binary file in the object code.
SKIPTO <addr> to move the address pointer to the specified address, generating an error if we are already beyond this address.
MAPCHAR command to allow strings to be assembled using non-ASCII codes (this is maybe more useful than it sounds; there's an example in the documentation).
Warns if there is no SAVE command in the source code.

The save command does need a small change as it always sets the high order bytes set to $00 which means it will load in the second processor if one is active. I think they need to add an IOSAVE command which forces $FF into these.