# PDF Labeling Editor
Ango Hub provides a labeling editor with which PDF files can be annotated.
{% hint style="info" %}
This article will exclusively go over Ango Hub’s PDF labeling interface. Features common to all labeling editors (audio, image, PDF, and text) are instead [explained here](https://docs.imerit.net/labeling/labeling-editor-interface).
{% endhint %}
## Overview
### Supported File Types
The PDF labeling editor supports document assets with the following file extensions:
* .pdf
### Supported Labeling Tools
The PDF labeling editor supports following labeling tools:
**Tools**
* PDF
**Classifications**
* Radio
* Checkbox
* Single-Select Dropdown
* Multi-Select Dropdown
* Single-Select Tree
* Multi-Select Tree
* Text
**Relations**
* Single Relation
* Group Relation
### PDF Interface Elements
#### Navigation buttons
The arrows allow you to move forwards and backward between pages. You can also directly type in the page number and press Enter to navigate to that page.
Scrolling with the mouse wheel will also navigate between pages in the asset.
With the + and - zoom buttons you can adjust the PDF's zoom level. resets the zoom level and jumps you to the bottom-most annotation in the PDF:
### How to Annotate PDFs
From the *Tools* panel on the left sidebar, select a *PDF* labeling tool, marked with an A enclosed in a square. (If none are present, only answer the questions in the *Questions* panel.)
#### Area
With the *PDF* tool selected, click and drag where you’d like the area to be placed.
After creating the area and selecting by clicking on it, you can change its size by dragging it from its sides and corners. You can drag the entire area by dragging it with the mouse cursor.
You can perform OCR on the contents of the box by selecting it by clicking it, then right-clicking on the box and pressing the *OCR* button.
After having performed OCR, you'll be shown how confident Hub is that the OCR it output is correct:
#### Nested Questions and Classifications
If the labels have nested questions, after selecting a label by clicking on it, right-click on a label and click on the menu item that appears to see and answer the nested questions.
If classification questions are present, you may answer them from the *Questions* panel on the left sidebar.
### Quick Annotation Navigation
Since PDFs can be long, manually navigating to where each label was placed can take time.
It is possible to directly "jump" to the location of each label by keeping Ctrl pressed and hovering over the label from the *Objects* section in the left sidebar. The editor will automatically navigate to the page where the label is, and the label selected will be highlighted.
### Keyboard Shortcuts
A full list of keyboard shortcuts is available by clicking on the *Keyboard* button on the right side of the top bar:
### Further reading
{% content-ref url="audio-labeling-editor" %}
[audio-labeling-editor](https://docs.imerit.net/labeling/labeling-editor-interface/audio-labeling-editor)
{% endcontent-ref %}
{% content-ref url="image-labeling-editor" %}
[image-labeling-editor](https://docs.imerit.net/labeling/labeling-editor-interface/image-labeling-editor)
{% endcontent-ref %}
{% content-ref url="" %}
[](https://docs.imerit.net/labeling/labeling-editor-interface)
{% endcontent-ref %}
resets the zoom level and 
jumps you to the bottom-most annotation in the PDF:
