Mitsubishi Electric MELSEC Q Series Structured Programming Manual page 110

Category
String that starts with K1
Such as K1AAA
to K8
Address Such as %IX0
;FB BLK START, ;FB START, ;FB END, ;FB BLK END, ;FB IN, ;FB
Statement in ladder
OUT, ;FB_NAME;,INSTANCE_NAME,
language
;FB, ;INSTANCE
Common instruction Such as MOV
COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8,
Windows reserved word COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8,
LPT9, AUX, CON, PRN, NUL
*1: Functions cannot be used.
*3: Applicable for Simple projects without labels only.
(1) Precautions on using labels
• In a function, the same name as the function cannot be used for a label.
• A space cannot be used.
• A numeral cannot be used at the beginning of label name.
• A label name is not case-sensitive. An error may occur at compilation when the same
• In structured ladder/FBD and ST programs, the same label name can be used for a global
• An underscore (_) cannot be used at the beginning or end of label name.
• For Simple projects, function names and function block names in common instructions
Appendix 2 Character Strings that cannot be Used in Label Names and Data Names
App-8
Table App. 2-1 Character strings that cannot be used for label names and data names (3/3)
Character string
label names with different cases (example: 'AAA' and 'aaa') are declared.
label and a local label by setting the following option in GX Works2
*1: Check the "Use the same label name in global label and local label" item under [Tool]  [Options] 
"Compile"  "Basic Setting".
Consecutive underscores (_) cannot be used for data name and label name.
and application functions can be used.
1
2 3 4 5

: Applicable, : With restrictions,
*1
6 7 8 9
 *1
*3

: Not applicable
.