I found a problem using the repeat command when I have " repeat 0 ".
I used the following code:
---------------------------
#chip 10F200, 4
#config  _MCLRE_OFF & _CP_OFF &  _WDT_OFF
movlw 0xC0
option
dir GPIO b'11111110'
repeat 0
nop
end repeat
end
----------------------------
the nop is repeated 255 times

in the assembler code the variable SysRepeatTemp1 is cleared,
nop is executed, the variable SysRepeatTemp1 is decresead and tested if zero, but at this point the value of SysRepeatTemp1 is 255 so, nop is repeated more times.  

the assembler code is:

;Program compiled by Great Cow BASIC (0.9 8/2/2007)
;Need help? See the GCBASIC forums at http://sourceforge.net/forum/?group_id=169286,
;check the documentation or email hconsidine@bigpond.com.

;********************************************************************************

;Set up the assembler options (Chip type, clock source, other bits and pieces)
LIST p=10F200, r=DEC
#include <P10F200.inc>
__CONFIG _MCLRE_OFF & _CP_OFF & _WDT_OFF

;********************************************************************************

;Set aside memory locations for variables
SysRepeatTemp1    equ    16

;********************************************************************************

;Jump to initialisation code when PIC is reset
    ORG    0
    call    INITSYS
    goto    SystemInitialise

;********************************************************************************

;Various initialisation routines, automatically called by GCBASIC
SystemInitialise

;********************************************************************************

;Start of the main program
    movlw    0XC0
    option   
    movlw    B'11111110'
    tris    GPIO
    clrf    SysRepeatTemp1
SysRepeatLoop1       
    nop   
    decfsz    SysRepeatTemp1,F
    goto    SysRepeatLoop1
    goto    BASPROGRAMEND
BASPROGRAMEND       
    sleep   
    goto    $
       
;********************************************************************************
;Subroutines included in program
;********************************************************************************
       
INITSYS       
    clrf    GPIO
    retlw    0
       
;********************************************************************************

END

Stefano