# n(b)/n(c) - Mask Definition

```
n(b) = { yappMaskDef } : If a yappMaskDef object is added it will be used as a mask 
                         for the cutout.
n(c) = { [yappMaskDef, hOffset, vOffset, rotation] } : If a list for a mask is added 
                         it will be used as a mask for the cutout. With the Rotation 
                         and offsets applied. This can be used to fine tune the mask
                         placement within the opening.
```

There are several predefined masks or you can create your own custom mask definition.

The following are the predefined masks:

* maskHoneycomb
* maskHexCircles
* maskCircles
* maskBars
* maskOffsetBars
* maskSquares

<figure><img src="/files/g9t2paxEdAbBaMAhVUsm" alt=""><figcaption></figcaption></figure>

To use a mask without modifiers **n(b)** you can simply list the mask name.  For example **maskHoneycomb**.

<figure><img src="/files/ZmV6rkMpZjYiSDkONumq" alt=""><figcaption><p><strong>maskHoneycomb</strong></p></figcaption></figure>

To use a mask with optional modifiers **n(c)** you can specify a vector (list enclosed in \[]'s) as follows:

```
[mask name, hOffset, vOffset, rotation]

mask Name = the masks name from the predefined list or a custom mask you have created.
hOffset = the distance in mm to shift the mask in the X axis (horizontal).  
    This will change how the mask aligns with the opening. 
vOffset = the distance to shift it in the Y axis (Vertical)
rotation = the angle to rotate the mask in reference to the cutout.

```

for example **\[maskHoneycomb, 0, 3.3, 30]**. This will select the honeycomb shaped mask with a vertical offset of 3.3mm and rotated 30 degrees.

<figure><img src="/files/V9ydCAc4XbEVC4EtU6ij" alt=""><figcaption><p><strong>[maskHoneycomb, 0, 3.3, 30]</strong></p></figcaption></figure>

you can only use n(b) or n(c) on the same object.

see [Mask Definition](/yappgenerator_en/advanced-options/mask-definitions.md) for how to create your own masks.


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