> ## Documentation Index
> Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# White Gap hypothesis

> Properties of a White Gap hypothesis in an Extraction Rules activity — Orientation, Histogram maximum, White Gap threshold, and search-among object types.

Hypotheses for **White Gap** elements are formulated by creating object histograms.

By default, a white gap is looked for among objects of the **Raw Object** type. To try and detect a white gap among other types of objects (e.g. separators), you need to specify an appropriate search condition in the additional search area properties for the **White Gap** element (Code Editor panel, **Search Conditions** section). For example, if you need to find a white gap in a region that can contain any type of object, use the expression `Type: PictureObject + SeparatorObject + AnyText + PunctuationMark + CheckMarkObject;`.

## White Gap hypothesis properties

A formulated White Gap hypothesis has the following type-specific properties (in addition to the general ones):

| Property | Description |
| :- | :- |
| Orientation | Specifies the orientation of the detected white gap. |
| Histogram maximum in search area | Specifies the maximum histogram value in the search area. |
| White Gap threshold | Specifies the calculated threshold for the histogram, over which the white gap will no longer be considered to be detected. |
| Histogram maximum within hypothesis | Specifies the maximum histogram value within the white gap hypothesis region. |