Security image
Some of the forms in the Scientific Volume Imaging websites use security images as 'captchas'. A captcha is a type of challenge-response test to determine whether or not the user is human (Wikipedia).
In order to prevent the automatic use of these forms by malintended users and spammers, you will be asked to type the characters that are shown distorted in the image:
(In this example you should enter
b2z4 as security code).When editing articles in this wiki anonymously, you may be asked to reply to this other captcha, in which you must enter the two English words (sometimes also numbers) shown distorted.
(In this example you should enter
overlooks inquiry separated by a space. If the displayed words are too difficult to read, you can either enter your best guess or click the reload button next to the distorted words.)This is a more sofisticated captcha from reCAPTCHA, and by replying to it you are also contributing to digitize old books.