> For the complete documentation index, see [llms.txt](https://aptivi.gitbook.io/aptivi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://aptivi.gitbook.io/aptivi/visualcard-manual/usage/how-to-use/parsers/durations-and-periods.md).

# Durations and Periods

Durations and periods of an event both describe how long an event will take, but in different formats.

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## <mark style="color:$primary;">Durations</mark>

VisualCard offers a duration parser that allows you to parse a string representation of the duration as specified in the ISO-8601:2004 format.

A single function that you can use is `GetDurationSpan()` from the `vCardCommonTools` class.

Once parsing is done, if the syntax is valid, it returns a tuple of both the `DateTimeOffset` that describes a resulting end date added to either a current date or a specified root date, and a `TimeSpan` that describes the processed duration.

{% hint style="info" %}
For vCalendar 2.0, month and year specifiers are not supported, but vCalendar 1.0 does. You can review the duration specifier [here](https://github.com/Aptivi/VisualCard/blob/main/VisualCard.Calendar/Specs/vcalendar-20-rfc5545.txt#L1929).
{% endhint %}

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## <mark style="color:$primary;">Periods</mark>

Periods describe a start date and an end date for a specific time ranged events, and can be described as a precise period of time. You can see its specification from the vCard 2.0 spec [here](https://github.com/Aptivi/VisualCard/blob/main/VisualCard.Calendar/Specs/vcalendar-20-rfc5545.txt#L2050).

`GetTimePeriod()` allows you to parse a period string and convert it to an appropriate `TimePeriod` class that has the following properties:

<table><thead><tr><th width="109.99993896484375">Property</th><th>Description</th></tr></thead><tbody><tr><td><code>StartDate</code></td><td>A <code>DateTimeOffset</code> instance that contains an event start date</td></tr><tr><td><code>EndDate</code></td><td>A <code>DateTimeOffset</code> instance that contains an event end date</td></tr><tr><td><code>Duration</code></td><td>A <code>TimeSpan</code> instance that contains a computed duration of a time period</td></tr></tbody></table>