=== XML Sitemap & Google News ===
Contributors: RavanH
Donate link: https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=ravanhagen%40gmail%2ecom&item_name=XML%20Sitemap%20Feed
Tags: sitemap, xml sitemap, news sitemap, sitemap.xml, robots.txt, Google, Google News, Yahoo, Bing, Yandex, Baidu, seo, feed, Polylang, WPML, image sitemap
Requires at least: 4.4
Requires PHP: 5.4
Tested up to: 5.3
Stable tag: 5.2.7

XML and Google News Sitemaps to feed the hungry spiders. Multisite, WP Super Cache, Polylang and WPML compatible.

== Description ==

This plugin dynamically creates feeds that comply with the **XML Sitemap** and the **Google News Sitemap** protocol. **Multisite**, **Polylang** and **WPML** compatible and there are no files created. There are options to control which sitemaps are enabled, which Post types are included, how Priority and Lastmod are calculated, who to ping and a possibility to set additional robots.txt rules from within the WordPress admin.

The main advantage of this plugin over other XML Sitemap plugins is **simplicity**. No need to change file or folder permissions, move files or spend time tweaking difficult plugin options.

You, or site owners on your Multisite network, will not be bothered with overly complicated settings like most other XML Sitemap plugins. The default settings will suffice in most cases.

An XML Sitemap Index becomes instantly available on **yourblog.url/sitemap.xml** (or yourblog.url/?feed=sitemap if you're not using a 'fancy' permalink structure) containing references to posts and pages by default, ready for indexing by search engines like Google, Bing, Yahoo, AOL and Ask. When the Google News Sitemap is activated, it will become available on **yourblog.url/sitemap-news.xml** (or yourblog.url/?feed=sitemap-news), ready for indexing by Google News. Both are automatically referenced in the dynamically created **robots.txt** on **yourblog.url/robots.txt** to tell search engines where to find your XML Sitemaps. Google and Bing will be pinged on each new publication.

Please read the FAQ's for info on how to get your articles listed on Google News.

**Compatible with caching plugins** like WP Super Cache, W3 Total Cache and Quick Cache that cache feeds, allowing a faster serving to the impatient (when hungry) spider.

**NOTES:**

1. If you _do not use fancy URL's_ or you have WordPress installed in a _subdirectory_, a dynamic **robots.txt will NOT be generated**. You'll have to create your own and upload it to your site root! See FAQ's.

2. On large sites, it is advised to use a good caching plugin like **WP Super Cache**, **Quick Cache**, **W3 Total Cache** or another to improve your site _and_ sitemap performance.

= Features =

* Compatible with multi-lingual sites using **Polylang** or **WPML** to allow all languages to be indexed equally.
* Option to add new robots.txt rules. These can be used to further control (read: limit) the indexation of various parts of your site and subsequent spread of pagerank across your sites pages.
* Includes XLS stylesheets for human readable sitemaps.

**XML Sitemap**

* Sitemap Index with optional inclusion of sitemaps for custom post types, categories and tags.
* Sitemap with custom URLs optional.
* Custom/static sitemaps can be added to the index.
* Works out-of-the-box, even on **Multisite** installations.
* Optionally include Image tags with caption and title for featured images or attached images.
* Pings Google, Bing & Yahoo on new post publication, once per hour.
* Options to define which post types and taxonomies get included in the sitemap
* Updates Lastmod on post modification or on comments.
* Set Priority per post type, per taxonomy and per individual post.
* Exclude individual posts and pages.

**Google News Sitemap**

* Required news sitemap tags: Publication name, language, title and publication date.
* Set a News Publication Name or uses site name.
* Supports custom post types.
* Limit inclusion to certain post categories.
* Pings Google on new publications, once per 5 minutes.

= Pro Features =

**[Google News Advanced](https://premium.status301.com/downloads/google-news-advanced/)**

* Multiple post types - Include more than one post type in the same News Sitemap.
* Keywords - Add the keywords tag to your News Sitemap. Keywords can be created from Tags, Categories or a dedicated Keywords taxonomy.
* Stock tickers - Add stock tickers tag to your News Sitemap. A dedicated Stock Tickers taxonomy will be available to manage them.
* Ping log - Keep a log of the latest pings to Google with exact date and response status.


= Privacy / GDPR =

This plugin does not collect any user or visitor data nor set browser cookies. Using this plugin should not impact your site privacy policy in any way.

**Data that is published**

An XML Sitemap index, referencing other sitemaps containing your web site's public post URLs of selected post types that are already public, along with their last modification date and associated image URLs, and any selected public archive URLs.

A Google News Sitemap containing your web site's public and recent (last 48 hours) URLs of selected news post type, along with their publication time stamp and associated image URL.

**Data that is transmitted**

Data actively transmitted to search engines is your sitemap location and time of publication. This happens upon each post publication when at least one of the Ping options on Settings > Writing is enabled. In this case, the selected search engines are alerted of the location and updated state of your sitemap.


= Contribute =

If you're happy with this plugin as it is, please consider writing a quick [rating](https://wordpress.org/support/plugin/xml-sitemap-feed/review/#new-post) or helping other users out on the [support forum](https://wordpress.org/support/plugin/xml-sitemap-feed).

If you wish to help build this plugin, you're very welcome to [translate it into your language](https://translate.wordpress.org/projects/wp-plugins/xml-sitemap-feed/) or contribute code on [Github](https://github.com/RavanH/xml-sitemap-feed/).

= Credits =

XML Sitemap Feed was originally based on the discontinued plugin Standard XML Sitemap Generator by Patrick Chia. Since then, it has been completely rewritten and extended in many ways.


== Installation ==

= Wordpress =

**I.** If you have been using another XML Sitemap plugin before, check your site root and remove any created sitemap.xml, sitemap-news.xml and (if you're not managing this one manually) robots.txt files that remained there.

**II.** Install plugin by:

Quick installation via **[Covered Web Services](http://coveredwebservices.com/wp-plugin-install/?plugin=xml-sitemap-feed)** !

 &hellip; OR &hellip;

Search for "xml sitemap feed" and install with that slick **Plugins > Add New** admin page.

 &hellip; OR &hellip;

Follow these steps:

1. Download archive.

2. Upload the zip file via the Plugins > Add New > Upload page &hellip; OR &hellip; unpack and upload with your favourite FTP client to the /plugins/ folder.

**III.** Activate the plugin on the Plugins page.

Done! Check your sparkling new XML Sitemap by visiting yourblogurl.tld/sitemap.xml (adapted to your domain name of course) with a browser or any online XML Sitemap validator. You might also want to check if the sitemap is listed in your yourblogurl.tld/robots.txt file.

= WordPress 3+ in Multi Site mode =

Same as above but do a **Network Activate** to make a XML sitemap available for each site on your network.

Installed alongside [WordPress MU Sitewide Tags Pages](http://wordpress.org/plugins/wordpress-mu-sitewide-tags/), XML Sitemap Feed will **not** create a sitemap.xml nor change robots.txt for any **tag blogs**. This is done deliberately because they would be full of links outside the tags blogs own domain and subsequently ignored (or worse: penalised) by Google.

= Uninstallation =

Upon uninstalling the plugin from the Admin > Plugins page, plugin options and meta data will be cleared from the database. See notes in the uninstall.php file.

On multisite, the uninstall.php *can* loop through all sites in the network to perform the uninstalltion process for each site. However, this does not scale for large networks so it *only* does a per-site uninstallation when `define('XMLSF_MULTISITE_UNINSTALL', true);` is explicitly set in wp-config.php.

== Frequently Asked Questions ==

= Where are the options? =

On **Settings > Reading** you can enable the XML Sitemap Index and (if needed) the Google News Sitemap. There is also an Additional robots.txt rules field.

Once a sitemap is enabled, its options can be found on **Settings > XML Sitemap** or on **Settings > Google News**.

Ping settings can be found on **Settings > Writing**.

= How do I get my latest articles listed on Google News? =

Go to [Suggest News Content for Google News](http://www.google.com/support/news_pub/bin/request.py?contact_type=suggest_content) and submit your website info as detailed as possible there. Give them the URL(s) of your fresh new Google News Sitemap in the text field 'Other' at the bottom.

You will also want to add the sitemap to your [Google Webmasters Tools account](https://www.google.com/webmasters/tools/) to check its validity and performance. Create an account if you don't have one yet.

= Can I manipulate values for Priority and Changefreq? =

You can find default settings for Priority on **Settings > XML Sitemap**. A fixed priority can be set on a post by post basis too.

Changefreq has been dropped since version 4.9 because it is no longer taken into account by Google.

= Do I need to submit the sitemap to search engines? =

No. In normal circumstances, your site will be indexed by the major search engines before you know it. The search engines will be looking for a robots.txt file and (with this plugin activated) find a pointer in it to the XML Sitemap on your blog. The search engines will return on a regular basis to see if your site has updates.

Besides that, Google and Bing are pinged upon each new publication by default.

**NOTE:** If you have a server _without rewrite rules_, use your blog _without fancy URLs_ (meaning, you have WordPress Permalinks set to the old default value) or have it installed in a _subdirectory_, then read **Do I need to change my robots.txt** for more instructions.

= Does this plugin ping search engines? =

Yes, Google and Bing are pinged upon each new publication. Unless you disable this feature on **Settings > Writing**.

= Do I need to change my robots.txt? =

In normal circumstances, if you have no static robots.txt file in your site root, the new sitemap url will be automatically added to the dynamic robots.txt that is generated by WordPress.

If you use a static robots.txt file in your website root, you will need to open it in a text editor. If there is already a line with `Sitemap: http://yourblogurl.tld/sitemap.xml` you can just leave it like it is. But if there is no sitemap referrence there, add it (adapted to your site url) to make search engines find your XML Sitemap.

Or if you have WP installed in a subdirectory, on a server without rewrite_rules or if you do not use fancy URLs in your Permalink structure settings. In these cases, WordPress will need a little help in getting ready for XML Sitemap indexing. Read on in the **WordPress** section for more.

= My WordPress powered blog is installed in a subdirectory. Does that change anything? =

That depends on where the index.php and .htaccess of your installation reside. If they are in the root while the rest of the WP files are installed in a subdir, so the site is accessible from your domain root, you do not have to do anything. It should work out of the box.

But if the index.php is together with your wp-config.php and all other WP files in a subdir, meaning your blog is only accessible via that subdir, you need to manage your own robots.txt file in your **domain root**. It _has_ to be in the root (!) and needs a line starting with `Sitemap:` followed by the full URL to the sitemap feed provided by XML Sitemap Feed plugin. Like:
`
Sitemap: http://yourblogurl.tld/subdir/sitemap.xml
`

If you already have a robots.txt file with another Sitemap reference like it, just add the full line below or above it.

= Do I need to use a fancy Permalink structure? =

No. While I would advise you to use any one of the nicer Permalink structures for better indexing, you might not be able to (or don't want to) do that. If so, you can still use this plugin:

Check to see if the URL yourblog.url/?feed=sitemap does produce a feed. Now manually upload your own robots.txt file to your website root containing:
`
Sitemap: http://yourblog.url/?feed=sitemap

User-agent: *
Allow: /
`
You can also choose to notify major search engines of your new XML sitemap manually. Start with getting a [Google Webmasters Tools account](https://www.google.com/webmasters/tools/) and submit your sitemap for the first time from there to enable tracking of sitemap downloads by Google! or head over to [XML-Sitemaps.com](http://www.xml-sitemaps.com/validate-xml-sitemap.html) and enter your sites sitemap URL.

= Can I change the sitemap name/URL? =

No. If you have fancy URL's turned ON in WordPress (Permalinks), the sitemap url is `yourblogurl.tld/sitemap.xml` but if you have the Permalink Default option set the feed is only available via `yourblog.url/?feed=sitemap`.

= I see no sitemap.xml file in my site root! =

There is no actual file created. The sitemap is dynamically generated just like a feed.

= I see a sitemap.xml file in site root but it does not seem to get updated! =

You are most likely looking at a sitemap.xml file that has been created by another XML Sitemap plugin before you started using this one. Remove that file and let the plugin dynamically generate it just like a feed. There will not be any actual files created.

If that's not the case, you are probably using a caching plugin or your browser does not update to the latest feed output. Please verify.

= I use a caching plugin but the sitemap is not cached =

Some caching plugins have the option to switch on/off caching of feeds. Make sure it is turned on.

Frederick Townes, developer of **W3 Total Cache**, says: "There's a checkbox option on the page cache settings tab to cache feeds. They will expire according to the expires field value on the browser cache setting for HTML."

The Google News sitemap is designed to NOT be cached.

= I get an ERROR when opening the sitemap or robots.txt! =

The absolute first thing you need to check is your blogs privacy settings. Go to **Settings > Privacy** and make sure you are **allowing search engines to index your site**. If they are blocked, your sitemap will _not_ be available.

Then, you might want to make sure that there is at least ONE post published. WordPress is known to send 404 status headers with feed requests when there are NO posts. Even though the plugin tries to prevent that, in some cases the wrong status header will get sent anyway and Google Webmaster Tools will report a vague message like:

    We encountered an error while trying to access your Sitemap.
    Please ensure your Sitemap follows our guidelines and can be
    accessed at the location you provided and then resubmit.

If that did not solve the issue, check the following errors that might be encountered along with their respective solutions:

**404 page instead of my sitemap.xml**

Try to refresh the Permalink structure in WordPress. Go to Settings > Permalinks and re-save them. Then reload the XML Sitemap in your browser with a clean browser cache. ( Try Ctrl+R to bypass the browser cache -- this works on most but not all browsers. )

**404 page instead of both sitemap.xml and robots.txt**

There are plugins like Event Calendar (at least v.3.2.beta2) known to mess with rewrite rules, causing problems with WordPress internal feeds and robots.txt generation and thus conflict with the XML Sitemap Feed plugin. Deactivate all plugins and see if you get a basic robots.txt file showing:
`
User-agent: *
Disallow:
`
Reactivate your plugins one by one to find out which one is causing the problem. Then report the bug to the plugin developer.

**404 page instead of robots.txt while sitemap.xml works fine**

There is a known issue with WordPress (at least up to 2.8) not generating a robots.txt when there are _no posts_ with _published_ status. If you use WordPress as a CMS with only _pages_, this will affect you.

To get around this, you might either at least write one post and give it _Private_ status or alternatively create your own robots.txt file containing:
`
Sitemap: http://yourblog.url/sitemap.xml

User-agent: *
Allow: /
`
and upload it to your web root...

**Error loading stylesheet: An unknown error has occurred**

On some setups (usually using the WordPress MU Domain Mapping plugin) this error occurs. The problem is known, the cause is not... Until I find out why this is happening, please take comfort in knowing that this only affects reading the sitemap in normal browsers but will NOT affect any spidering/indexing on your site. The sitemap is still readable by all search engines!

**XML declaration allowed only at the start of the document**

This error occurs when blank lines or other output is generated before the start of the actual sitemap content. This can be caused by blank lines at the beginning of wp-config.php or your themes functions.php or by another plugin that generates output where it shouldn't. You'll need to test by disabling all other plugins, switching to the default theme and manually inspecting your wp-config.php file.

= I see only a BLANK (white) page when opening the sitemap =

There are several cases where this might happen.

Open your sitemap in a browser and look at the source code. This can usually be seen by hitting Ctrl+U or right-click then select 'View source...' Then scan the produced source (if any) for errors.

A. If you see strange output in the first few lines (head tags) of the source, then there is a conflict or bug occuring on your installation. Please go to the [Support forum](http://wordpress.org/support/plugin/xml-sitemap-feed) for help.

B. If the source is empty or incomplete then you're probably experiencing an issue with your servers PHP memory limit. In those cases, you should see a messages like `PHP Fatal error: Allowed memory size of xxxxxx bytes exhausted.` in your server/account error log file.

This can happen on large sites. To avoid these issues, there is an option to split posts over different sitemaps on Settings > XML Sitemap. Try different settings, each time revisiting the main sitemap index file and open different sitemaps listed there to check.

Read more on [Increasing memory allocated to PHP](http://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP) (try a value higher than 256M) or ask your hosting provider what you can do.

= Can I run this on a WPMU / WP3+ Multi-Site setup? =

Yes. In fact, it has been designed for it. Tested on WPMU 2.9.2 and WPMS 3+ both with normal activation and with Network Activate / Site Wide Activate.


== Screenshots ==

1. XML Sitemap feed viewed in a normal browser. For your eyes only ;)
2. XML Sitemap source as read by search engines.


== Upgrade Notice ==

= 5.2.7 =

New action hooks, Ad Inserter compatibility check.


== Changelog ==

= 5.2.7 =
* NEW: Ad Inserter compatibility check
* NEW: xmlsf_urlset and xmlsf_news_urlset action hooks, thanks to Stanislav Khromov (@khromov)
* Exclude hierarchical post types from news sitemap

= 5.2.6 =
* NEW: xmlsf_tags_after, xmlsf_url_after and xmlsf_news_url_after action hooks
* Make stylesheet paths relative to prevent exclusion when using different language domains
* FIX: Taxonomy selection not available to new installs

= 5.2.4 =
* NEW Rank Math incompatibility admin warnings
* FIX undefined index
* FIX invalid form control

= 5.2.3 =
* FIX Cannot use return value in write context
* FIX issue #30 for sql_mode=ONLY_FULL_GROUP_BY, thanks @silvios
* FIX invalid form control not focusable when meta box is hidden

= 5.2.2 =
* FIX invalid date format on some PHP versions
* FIX Can't use function return value in write context
* FIX non-cyrillic URLs stripped from External Web Pages field
* FIX Call to undefined function xmlsf_cache_get_archives()

= 5.2 =
* Image query optimization and meta caching
* Last comment date meta caching
* Lastmod and publication dates in local time
* Removed ignored image tag from news sitemap
* Max memory limit for post type and taxonomy term sitemaps
* Prevent CDN file urls
* Zlib before GZhandler on .gz request
* FIX: don't ping for excluded posts
* FIX: traditional and simplified Chinese with WPML
* FIX: redundant front page url
* FIX: array_filter() expects parameter 1 to be array
* FIX: possible division by zero
* FIX: update_term_modified_meta
* FIX: rewrite rules on deactivate/uninstall

= 5.1.2 =
* FIX: admin notice dismiss button failing
* FIX: date archive redirect notice showing for inactive post types
* Plugin support and rate links on plugins page

= 5.1.1 =
* FIX options page not found
* FIX news sitemap only ping

= 5.1 =
* SEOPress and Catch Box incompatibility admin messages
* FIX bbPress incompatibility
* FIX failing last modified date for taxonomy sitemaps
* FIX sitemap showing when only private posts
* FIX possible sitemaps for no longer existing post types in index
* Admin interface improvements: highlighting and scroll
* Upgrade routines in own class only to be included when needed
* Moved metabox methods to dedicated classes
* NEW Respond to .gz requests (with ob_gzhandler output buffering if needed)
* NEW filters xmlsf_disabled_taxonomies, xmlsf_news_keywords, xmlsf_news_stock_tickers
* NEW action xmlsf_ping
* NEW Tools: Ping search engines and Flush rewrite rules

= 5.0.7 =
* Allowed domains back to Settings > Reading
* FIX static files check on activation
* NEW Admin warning on conflicting plugin settings
* FIX Empty post priority saved as 0.0
* FIX Call to undefined function xmlsf_get_archives()
* FIX force LC_NUMERIC locale to C
* FIX Call to private method
* FIX Custom post types with a hyphen not showing
* FIX Admin static files message fatal error, thanks @kitchin
* FIX Improper if statement in upgrade routine, thanks @kitchin
* FIX PHP 5.4 compatibility issues

= 5.0 =
* Complete code restructure and cleanup: MVC and JIT inclusion
* Fewer DB queries, much smaller memory footprint on normal queries
* NEW Admin interface with dedicated options pages and help tabs
* NEW Taxonomy term options: priority and automatic calculation
* NEW Admin warning on conflicting static files
* NEW Option to delete conflicting static files
* NEW Filters for post types: xmlsf_post_types and xmlsf_news_post_types
* NEW Filters for priority values: xmlsf_post_priority and xmlsf_term_priority
* Removal of Genre, Keywords and Access tags as Google dropped support
* Taxonomy term sitemaps speed improvement: get lastmod date from database
* Exclude Woocommerce product_shipping_class taxonomy
* PHP 7.2+ compat: create_function deprecated
* No more domain filtering for custom URLs and sitemaps
* FIX Gutenberg editor GN genre taxonomy not showing
* FIX Plain and /index.php/ permalink structure
* FIX Clear all options on uninstall
* FIX Pings

= 4.9.4 =
* FIX: missing featured images, thanks @flyerua
* FIX: double content type response header filtering

= 4.9.3 =
* Reinstate filter_no_news_limits, allowing post type array
* Improved language handling and new language filter xmlsf_post_language
* Force text/xml Content-Type response header

= 4.9.2 =
* FactCheck genre causes error in Search Console

= 4.9.1 =
* FIX: double genre terms on upgrade from 4.4,  thanks @mouhalves
* FIX: wp_count_posts uncached and too heavy on large sites, thanks @carlalexander
* Last-modified response header now linked to Update on comments setting
* FIX: plugin_basename propagation

= 4.9 =
* Code cleanup
* NEW: FactCheck genre
* Changefreq tag dropped
* NEW: translation strings for genres
* FIX: zlib.output_compression compatibility, thanks @alicewondermiscreations
* FIX: permalink issue with Woocommerce account page endpoints
* FIX: undefined index in news post types

= 4.8.3 =
* fix get_lastpostdate array/string
* restore pre PHP 5.4 compatibility (popular request)

= 4.8 =
* NEW: Conditional functions is_sitemap() and is_news()
* code cleanup and annotation
* new google ping URL
* revisit get first/last date/modified functions and cache key set/delete
* FIX: cache key missing timezone
* FIX: wp_rewrite init before flush_rules

= 4.7.6 =
* FIX Open_BaseDir issue on IIS server

= 4.7.5 =
* FIX: On cache_flush purge also the respective time_key cache entry,
props @e2robert https://wordpress.org/support/topic/object-cache-issue-results-in-outdated-last-modified-values-on-index-sitemap/
* FIX: Variable variable php 7 compat
* Detect if headers are already sent and print warning in source

= 4.7.4 =
* Another WPML compat issue fixed, special thanks to hermes3por3

= 4.7.3 =
* NEW: xmlsf_excluded filter
* IMPROVEMENT: Polylang and WPML compatibility issues
* FIX: "Only variables should be passed by reference" strict warning
* FIX: PHP 5.3 compatibility

= 4.7 =
* WPML compatibility
* FIX: News Sitemap chinese language tag
* FIX: flush rules on plugin re-activation

= 4.6.3 =
* NEW: filter xmlsf_custom_sitemaps
* BUGFIX: empty custom urls sitemap

= 4.6.2 =
* NEW: filter xmlsf_custom_urls
* More cleanup
* BUGFIX: broken Polylang compatibility reported by @zesseb

= 4.6.1 =
* Code cleanup
* POT file update
* Dutch translation update

= 4.6 =
* NEW: xmlsf_news_tags_after action hook
* Attempt to remove static sitemap files left over by other sitemap plugins

= 4.5.1 =
* fix Persistent/Stored XSS vulnerability on admin page, thanks to Sneha Rajguru @Sneharajguru

= 4.5 =
* Set Google News access tag per post
* Exclude posts from Google News sitemap
* News Sitemap stylesheet text/links update
* FIX: cache_delete cached key instead of cache_flush as suggested by Jeremy Clarke https://wordpress.org/support/topic/please-stop-running-wp_cache_flush-whenever-posts-are-edited
* NEW: Nginx Helper compatibility to purge cache sitemap URLs from FastCGI Cache or Redis

= 4.4.1 =
* BUGFIX contribution by alejandra.aranibar: multiple news post types makes get_lastdate return oldest instead of newest date
* BUGFIX plugins_url filter not working, reported by Michael
* Dropped GN Geolocation tag support
* Dropped XMLSF_POST_TYPE and XMLSF_NEWS_POST_TYPE defines support
* Multiple default genres

= 4.4 =
* Pings max once per hour (5 minutes for news sitemap)
* Seperate ping for Google News Sitemap
* Append custom/static sitemaps to the index
* Include other post types in News Sitemap
* Optionally limit posts to certain categories in News Sitemap
* Noindex response header for sitemaps to keep them out of search results
* Static sitemap stylesheets
* Controversial default robots.txt rules removed
* DB query streamlining
* BUGFIX: fatal error on . (dot) as category base in permalinks
* BIGFIX: PHP Strict notices
* Force object cache flush on post publication

= 4.3.2 =
* Italian translation
* BUGFIX: html esc / filter image title and caption tags
* BUGFIX: empty terms counted causing empty taxonomy sitemap appearing in index
* BUGFIX: custom taxonomies where lastmod cannot be determined show empty lastmod tag

= 4.3 =
* Google News sitemap settings section
* Google News tags: access, genres, keywords, geo_locations
* Improved Google News stylesheet
* Custom Google News Publication Name
* Image tags in Google News sitemap
* Custom URLs
* Allow additional domains
* Image caption and title tags
* Ping Yandex and Baidu optional
* BUGFIX: Ineffective robots.txt rules
* BUGFIX: Priority value 0 in post meta not saved
* BUGFIX: Ping for all post types
* BUGFIX: Custom taxonomy support
* BUGFIX: Split by month shows year

= 4.2.4 =
* NEW: Image tags
* Rearranged settings section
* FIX: replace permalink, title and bloginfo rss filter hooks with own

= 4.2.3 =
* BUGFIX: Empty ping options after disabling the main sitemap
* BUGFIX: Empty language tag for Google News tags in posts sitemap
* Small back end changes
* NEW: Custom post types split by year/month

= 4.2 =
* NEW: Image & News tags
* NEW: Exclude pages/posts

= 4.1.4 =
* BUGFIX: Pass by reference fatal error in PHP 5.4
* BUGFIX: issue with Polylang language code in pretty permalinks setting
* BUGFIX: unselected post types in sitemap
* BUGFIX: 1+ Priority for sticky posts with comments
* Dutch and French translations updated

= 4.1 =
* NEW: Ping Google and Bing on new publications
* NEW: Set priority per post
* NEW: Priority calculation options
* NEW: Option to split posts by year or month for faster generation of each sitemap
* Reduced queries to increase performance
* Improved Lastmod and Changefreq calculations
* Core class improvements
* Dropped qTranslate support
* Dropped PHP4 support
* BUGFIX: removed several PHP notices

= 4.0.1 =
* NEW: Dutch and French translations
* BUGFIX: Non public sites still have sitemap by default
* BUGFIX: Invalid argument supplied for foreach() when all post types are off
* BUGFIX: Wrong translation dir

= 4.0.0 =
* Moved to sitemap index and seperated post/page sitemaps
* NEW: options to dswitch off sitemap and news sitemap
* NEW: select which post types to include
* NEW: select which taxonomies to include
* NEW: set additional robots.txt rules
* NEW: Translation POT catalogue
* Improved Polylang support
* Dropped xLanguage support
* qTranslate currently untested

= 3.9.2 =
* Basic Google News feed stylesheet
* improvement on XSS vulnerability fix
* Fixed trailing slash

= 3.9.1 =
* SECURITY: XSS vulnerability in sitemap.xsl.php

= 3.9 =
* Google News Sitemap
* Memory limit error workaround (for most sites)

= 3.8.8 =
* BUGFIX: PHP4 compatibility
* BUGFIX: stylesheet URL when installed in mu-plugins
* core change to class
* minified sitemap output by default

= 3.8.5 =
* **xLanguage support** based on code and testing by **Daniele Pelagatti**
* new FILTER HOOK `robotstxt_sitemap_url` for any translate and url changing plugins.
* BUGFIX: Decimal separator cannot be a comma!

= 3.8.3 =
* filter out external URLs inserted by plugins like Page Links To (thanks, Francois)
* minify sitemap and stylesheet output
* BUGFIX: qTranslate non-default language home URL

= 3.8 =
* **qTranslate support**
* no more Sitemap reference in robots.txt on non-public blogs

= 3.7.4 =
* switch from `add_feed` (on init) to the `do_feed_$feed` hook
* BUGFIX: `is_404()` condition TRUE and Response Header 404 on sites without posts
* BUGFIX: `is_feed()` condition FALSE after custom query_posts
* BUGFIX: no lastmod on home url when only pages on a site
* BUGFIX: stylesheet url wrong when WP installed in a subdir

= 3.7 =
* massive changefreq calculation improvement
* further priority calulation improvement taking last comment date into account

= 3.6.1 =
* BUGFIX: wrong date calculation on blogs less than 1 year old

= 3.6 =
* massive priority calculation improvement

= 3.5 =
* complete rewrite of plugin internals
* speed improvements
* WP 3.0 (normal and MS mode) ready

= 3.4 =
* BUGFIX: use home instead of siteurl for blog url for sitemap reference in robots.txt
* code streamline and cleanup

= 3.3 =
* automatic exclusion of tags blog in wpmu

= 3.2 =
* rewrite and add_feed calls improvements
* BUGFIX: double entry when static page is frontpage

= 3.0 =
* added styling to the xml feed to make it human readable

= 2.1 =
* BUGFIX: lastmod timezone offset displayed wrong (extra space and missing double-colon)

= 2.0 =
* priority calculation based on comments and age
* changefreq based on comments

= 1.0 =
* changed feed template location to avoid the need to relocate files outside the plugins folder
* BUGFIX: `get_post_modified_time` instead of `get_post_time`

= 0.1 =
* rework from Patrick Chia's [Standard XML Sitemaps](http://wordpress.org/plugins/standard-xml-sitemap/)
* increased post urls limit from 100 to 1000 (of max. 50,000 allowed by the Sitemap protocol)
