# Property Filter

The **Property Filter** is the most general type of filter.

In theory, this type can do the job of all the other filter types. But remember this filter is complex.

The software must evaluate the expression and interrogate the item for each property the expression uses; which may result in slower performance.

The **Property Filter** is a mathematical expression which you can edit as simple text. The expression can use item properties as well as numbers.

**TIP: **See Property Expression Syntax for more details.

To see whether an item passes the filter the expression is evaluated. If the expression evaluates to a non-zero value the item is included.

Here are some examples of expressions:

`_FC&=1`

_FC&<>98

(_FC&=1) or (_FC&=1006) or (_FC&=98)

(_FC&=1) and _closed&

_class$="Line"

_np&>78

len(_text$)>6

grep("[0123456789]",_text$)

Some item properties may appear esoteric (like Thin in X and Thin in Y) but they can be useful (for instance to find horizontal and vertical lines as part of a data cleaning exercise).