Privacy

What this site collects

No account is required to read anything here, and none can be created. There is no comment system, no newsletter and no contact form; the only way to send something to the site is to write to the address on the contact page.

The web server keeps a standard access log: the requested address, the time, the referring page, the browser's user-agent string and the connecting IP address. These logs are used to keep the site running and to spot abuse, and they are rotated on a short schedule.

Advertising, including Google AdSense

This site may display advertising served by Google AdSense and by other third-party vendors. Third-party vendors, including Google, use cookies to serve ads based on a user's prior visits to this website or other websites. Google's use of advertising cookies enables it and its partners to serve ads to users based on their visit to this site and/or other sites on the internet.

You may opt out of personalised advertising by visiting Google's Ads Settings (adssettings.google.com). Alternatively, you can opt out of a third-party vendor's use of cookies for personalised advertising by visiting aboutads.info. Where required, a consent message is shown before any non-essential cookie is set, and the choice can be changed at any time from the same message.

Google AdSense may also use the DoubleClick DART cookie, which serves ads based on visits to this and other sites. If you have not opted out of third-party ad serving, the DART cookie may be used. Details and the opt-out are available in Google's advertising policies.

Your rights under GDPR and CCPA

If you are in the European Economic Area, the United Kingdom or Switzerland, you have the right to access, correct, delete or restrict processing of personal data that concerns you, and the right to object to processing based on legitimate interests. If you are a California resident, you have the right to know what personal information is collected, to request deletion of it, and to opt out of the sale or sharing of personal information. This site does not sell personal information.

Because this site has no accounts, the personal data it holds is limited to the server access log described above. Requests about it can be sent to the address on the contact page and will be answered within the period the applicable law allows.

Where a consent banner is shown, declining personalised advertising has no effect on what you can read here: every page is served identically whether or not advertising cookies are accepted.

Embedded content and external links

Pages here may link to other sites. Once you follow a link, the privacy policy of that site applies. No third-party embeds that set cookies are used for the figures on this site; the diagrams are generated files served from this domain.

Fonts are loaded from a font service, which means your browser makes a request to that service when a page loads. That request includes your IP address and user-agent, as any request to any server does.

Changes to this policy

If what is collected changes, this page changes with it and the date below moves. The site does not add a tracking feature without saying so here first.