node tag 08 or 09

[EricsonEncinaZ]

While testing a procedure I used 3 nested "for" cycles to define a regular 3D node scheme as shown below:

for {set i 0} {$i<=10} {incr i} {
for {set j 0} {$j<=10} {incr j} {
for {set k 0} {$k<=10} {incr k} {
set nodo [concatenate $i $j $k]
node $nodo $i $j $k
}
}
}

Where concatenate just puts together the values passed. All worked properly except when the node tag was 008 or 009 (I made it work by adding a 1 at the front). Then I manually tried to define a node with a tag 08, 0008, etc. and none of them could be defined. The error OpenSees returns is:
WARNING invalid nodeTag
Want: node nodeTag? [ndm coordinates?] <-mass [ndf values?]>
expected integer but got "008"

I also tried with OpenSees version 2.4.4, 2.4.6, 2.5.0 and all of them returned the same result.

Why one cannot define a node as 08 or 09, being that 01-07 show no problem?

[fmk]

in tcl, a leading 0 indicates to the interpreter the number is an octal number!