Lotus 域类型（可编辑，计算，创建时计算、显示时计算）

Type of computed field	Formula calculates
Edit 编辑	You choose whether a field is editable or computed in the field properties box, when you create the field. If a field is editable, a user can enter or change the value of the field. If a field is computed, a formula calculates the field value. Users can't change the values in a computed field. Number, date/time, authors, readers, and names fields are usually computed. Text, rich text, and choice list fields are usually editable. 当文档是编辑状态时，用户可以编辑此域的信息，该域的可编辑状态与文档相同。大部分域使用这种域，用于用户填写信息。
Computed 计算	A computed field formula calculates each time a user creates, saves, or refreshes a document. 该域类型在任何状态下都是不可编辑的，每次文档保存的时候，该域都会根据公式进行值的计算，然后将计算结果写到到文档对应的域值中，常用的。
Computed when composed 创建时计算	A computed-when-composed field formula calculates only once: when the user first creates the document. Use this type of formula in a field to preserve information about the origin of a document, such as the creation date or original author, or to create a field whose original value never changes, such as a document sequence number. 该域类型也是在任何状态下都是不可编辑的，创建文档的时候该域生成，并且在文本编辑的时候，该域不会随着文档的变化而重新进行计算。常用到的比如确定文档的创建者，只需要在域默认值中写入@username就OK，以后不管是谁编辑，该值永远是文档的创建者，这个是和普通计算域的区别。
Computed for display 显示时计算	A computed-for-display field formula recalculates each time a user opens or saves a document. Use this type of formula in a field to display information that is relevant only to the immediate session, such as the current time or the results of calculations that you don't need to save. The field value exists during the current session only and is not stored. You cannot display the contents of a computed­for­display field in a view 类似计算文本，当文档打开的时候，根据域中的公式现去计算该域的值。注意一点，显示时计算域，在文档保存时，不保存该域的真实值，永远是空，也就是说，你定义了一个显示时计算域，则只能在前台使用，后台（代理等）无法使用这个域。.

http://blog.youkuaiyun.com/chwxj/article/details/6589372