/// <summary>
/// Filter on content properties. There are two types of filters; simple and advanced. The advanced one is used
/// if the properties in the filter are to contain special characters, i.e. other characters than a-z,A-Z,0-9,_,=,#.
/// The property filter is a logical expression combining properties
/// You can use && (AND), || (OR), ( ) (parenthesis) and ! (NOT) in expressions. Optional parameter.
/// <para>
/// Note that spaces within a simple property filter must be replaced by # (hash mark/number sign). If not, the expression parser will fail.
/// </para>
/// <para>
/// Example on expression syntax for simple filters:
/// !Type=Film && (Actor=Tom#Hanks || Category=Toplist)
/// </para>
/// <para>
/// For advanced filters, when special characters are used, the <see cref="FindContentParameters.PropertiesFilterParameters"/>
/// list must be used to send the property matchings. %1, %2, etc are placeholders for the
/// property parameter.
/// </para>
/// <para>
/// Example on expression syntax for complex filters:
/// !%1 && (%2 || %3)
/// where %1 is a <see cref="PropertiesFilterParameter"/> with <see cref="PropertiesFilterParameter.PropertyName"/> set to TÃ¥|p and
/// <see cref="PropertiesFilterParameter.PropertyMatchString"/> is set to F!lm etc.
/// </para>
/// </summary>
// NON-XML-doc example: !Type=Film && (Actor=Tom#Hanks || Category=Toplist)
[DataMember(IsRequired = true)]
public String PropertiesFilter;

/// <summary>
/// When advanced property filters are used where the properties contain special characters,
/// see <see cref="FindContentParameters.PropertiesFilter"/>,
/// this list must be filled with the properties. The first value in the list matches the
/// placeholder %1, the second one %2, etc. The values in this list can contain any character
/// </summary>
[DataMember]
public List<PropertiesFilterParameter> PropertiesFilterParameters;

Snippet from the code ref. explaining PropertiesFilter in FindContent

PropertyFilter code ref document

C#