Writing contrast using spline & a binary variable

[PamG]

I have two variables - spline variable of height and a binary variable.  How do I write contrast to get difference in spline effects with respect to a reference at height=50 when sex=M and sex=F?  How can this be wriiten using positional syntax?

data Have(rename=(height=BMI));
set sashelp.class;
keep Height sex age;
run;

proc phreg data=have;
class sex(ref="F")/param=ref;
effect bmiS=spline(bmi/ basis=tpf(noint) NATURALCUBIC details knotmethod=percentiles(4));
model age=sex bmiS bmiS*sex;
store result;
run;

%LET ref=50; %LET value=65;

proc plm restore=result;
**for females;
estimate "1. &value. VS &ref. sex level 1" bmis [-1, &ref.] [1, &value.] sex*bmis [-1, 1 &ref.] [1, 1 &value.]/ e exp cl;* cov;
estimate "2. &value. VS &ref. " bmis [-1, &ref.] [1, &value.] / e exp cl;* cov;

**for males;
estimate "3. &value. VS &ref. sex level 2" sex 1 bmis [-1, &ref.] [1, &value.] sex*bmis [-1, 2 &ref.] [1, 2 &value.]/ e exp cl;* cov;
estimate "4. &value. VS &ref. sex level 2 (ref)" sex 1 bmis [-1, &ref.] [1, &value.] sex*bmis [-1, 2 &ref.] [1, 2 &value.]/ e exp cl;* cov;

run;

[PamG]

I would like to know if the above contrast is correct and how can this be written using positional syntax.  Thanks.