validate_LN with MODE_L:
Positive (valid):
L 
L+ 
L- 
L+1
L-1 
L+9
L-9
L+10
L-10
L+50
L-50
L+90
L-90
L+100
L-100
L+47383
L-8877843
L1
L5
L9
L10
L11
L50
L90
L100
L84355
L2374827364

Negative (invalid AKA '?'):
L+0
L-0
L0 
L01212332
L0+ 
L+0+
L+0+0
L+1+0
L+4-
L-0+10
LL
LL+
L+L
L+L12 
L+L+100
L000000000000000000000000
L+000000000000000000000
L10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
L+10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
L-10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
L+10000000000000000000000000000 (31 chars)
L+1000000000000000000000000000L (31 chars)
L+100000000000000000000000000L  (30 chars)
L?
L?1
L?1000
LL100000
L1000?

Overall results: Tested OK

validate_LN with MODE_N:
Positive (valid):
N 
N+  
N+1
N+9
N+10
N+50
N+90
N+100
N+47383
N1
N5
N9
N10
N11
N50
N90
N100
N84355
N2374827364

Negative (invalid AKA '?'):
N-
N-1
N-9
N-10
N-11
N-50
N-90
N-100
N-26347234
N-10+
N+10-
N+10+10
N0 
N+0
N+01
N04453
N+04343
N-02343
N03413
N++
N--
N+10+10
N-10-10
N++10
N--10
NN
NNNNN
N?10
N?999999
N?
NL

Overall results: Tested OK.