# Setting new border label by modifying the former border

**URL:** <https://community.freefem.org/t/setting-new-border-label-by-modifying-the-former-border/1335>\
**Category:** General Discussion\
**Created:** [November 18, 2021, 8:22am UTC](https://community.freefem.org/t/setting-new-border-label-by-modifying-the-former-border/1335 "2021-11-18T08:22:18Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![zese](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zese/32/917_2.png) [@zese](https://community.freefem.org/u/zese)\
**Post date:** [November 18, 2021, 8:22am UTC](https://community.freefem.org/t/setting-new-border-label-by-modifying-the-former-border/1335/1 "2021-11-18T08:22:18Z")

</div>

Dear all

I have an airfoil which I introduced as follow in FF++. now I want to specify some sluts on the airfoil and change the label. do you know how I can do that?

real CC = 0.95105651629515357211643933337938;

real SS = -0.30901699437494742410229341718282;

// Mesh

border Splus(tt=0., 1.){real t=tt^1.5;x=CC_t -SS_1.25\*( (0.17735_sqrt(t) - 0.075597_t - 0.212836\*(t^2) + 0.17363\*(t^3) - 0.06254\*(t^4)) );

```
                                                                               y=SS*t+CC*1.25*(0.17735*sqrt(t) - 0.075597*t - 0.212836*(t^2) + 0.17363*(t^3) - 0.06254*(t^4));    

                                                                                            label=2;} // the upper airfoil surface

```

border Sminus(tt=1., 0.){real t=tt^1.5;x=CC_t - SS_1.25\*(-(0.17735_sqrt(t) - 0.075597_t -0.212836\*(t^2) + 0.17363\*(t^3) - 0.06254\*(t^4)));

```
                                                                               y=SS*t +CC*1.25*(-(0.17735*sqrt(t) - 0.075597*t -0.212836*(t^2) + 0.17363*(t^3) - 0.06254*(t^4)));

                                                                                            label=2;}

```

![2021-11-18_11-49-28](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/1X/b574efb421cce28e1ec958f7bba2df6aa54fe8a8.jpeg)