What is Tolerance
Tolerance is accommodating for mistakes and errors of users. This is shown in spell check applications. The program is tolerant to errors and suggests corrections to compensate. This can be done well when it makes known the possible corrections but does not decide it for you. With some cell phone spell checks it makes the decision for you which often frustrates to no end as it is to tolerant.
“Compliance and tolerance means to allow inconsequential deviation from a rigid format. Allow dates and telephone numbers in any form that a person would understand. Allow flexibility, allow tolerance for small deviations.” -Don Norman, http://www.jnd.org/dn.mss/interaction-articles.html
Tolerance is to compensate for human errors and not to punish the user. When well done tasks become easier as you are alerted of possible errors before you follow though with them. Sometimes you want to do what the object does not want you do and that must be allowed to be overridden.