Is nonlinear stiffness allowed for SPRING1 elements?

I’m trying to set up a model using SPRING1 elements with a nonlinear spring constant.

As a test, to make sure I’m formatting things correctly, the following input file works using a linear constant and gives the expected result.

*NODE,NSET=NALL
1,0.,0.,0.
*ELEMENT,TYPE=SPRING1,ELSET=EALL
1,1
*SPRING,ELSET=EALL
1
1.E6
*BOUNDARY
1,2,3
*STEP
*STATIC
*CLOAD
1,1,10.
*NODE PRINT,NSET=NALL
U,RF
*END STEP

However when I change the spring to be nonlinear, such as the following, and using any arbitrary set of spring constants:

*NODE,NSET=NALL
1,0.,0.,0.
*ELEMENT,TYPE=SPRING1,ELSET=EALL
1,1
*SPRING,NONLINEAR,ELSET=EALL
1
-1.E6,-1.
0.,0.
1.E6,1.
*BOUNDARY
1,2,3
*STEP
*STATIC
*CLOAD
1,1,10.
*NODE PRINT,NSET=NALL
U,RF
*END STEP

ccx exits with the error:

*ERROR reading *SPRING: a degree
of freedom was specified
(no decimal point in entry),
however, there are neither
SPRING1 nor SPRING2 elements
in the input deck
*ERROR reading *SPRING. Card image:
1
*ERROR in calinput: no material was assigned
to element 1

Am I doing something wrong? Are nonlinear SPRING1 elements supported? If it matters I’m using version 2.17.

Hello ,
have you looked in the manual ? or tested / looked into the attached examples ?
maybe you find there a solution:

image