Dwg precision and Osnap

I have 2 line with common endpoint with a very
little Y difference:

(for the functions see below)

Comando: ALE_SHOWPRECISION
Select object: <<< select 1° line
55.24999997642098 - 21.50000000003609 <<< PtX
134.2499999764369 - 21.50000000003609

Comando: ALE_SHOWPRECISION
Select object: <<< select 2° line
55.24999997642098 - 15.5
55.24999997642098 - 21.5 <<< PtX

Comando: _line
First point: _int <<< intersec of 2 lines (PtX)
Next point: 0,0

Comando: ALE_SHOWPRECISION
Select object: <<< select new line (3°)
55.24999997642098 - 21.50000000003609 <<< PtX
0 - 0

Y 1° line = 21.50000000003609
Y 2° line = 21.5
Y 3° line = 21.50000000003609

--

Questions:

1) what is the minimum distance to get an osnap error

2) why the new line (3°) has the Y of 1° line and
not the Y of 2° line

--

(defun C:ALE_ShowPrecision ( / EntNam EntDat Pnt001 Pnt002)
(setq
EntNam (car (nentsel "\nSelect object: "))
EntDat (entget EntNam)
Pnt001 (cdr (assoc 10 EntDat))
)
(princ (strcat "\n" (rtos (car Pnt001) 2 16)))
(princ (strcat " - " (rtos (cadr Pnt001) 2 16)))
(cond
( (wcmatch (DXF 0 EntDat) "LINE,TEXT,ATTRIB,ATTDEF")
(setq Pnt002 (cdr (assoc 11 EntDat)))
(princ (strcat "\n" (rtos (car Pnt002) 2 16)))
(princ (strcat " - " (rtos (cadr Pnt002) 2 16)))
)
( (= (DXF 0 EntDat) "LWPOLYLINE")
(foreach ForElm (cdr (ALE_Massoc 10 EntDat))
(princ (strcat "\n" (rtos (car ForElm) 2 16)))
(princ (strcat " - " (rtos (cadr ForElm) 2 16)))
)
)
)
(princ)
)
; Orginal by M. Puckett
(defun ALE_MAssoc (DxfKey ImpLst / TmpLst OutLst)
(while (setq TmpLst (assoc DxfKey ImpLst))
(setq OutLst (cons (cdr TmpLst) OutLst)
ImpLst (cdr (member TmpLst ImpLst))
)
)
(reverse OutLst)
)


--

Marc'Antonio Alessi
http://xoomer.virgilio.it/alessi
(strcat "NOT a " (substr (ver) 8 4) " guru.")

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