Starting from package 167, form API version 1.0 is not supported.

According to Forms API 1.0 model, form calculations are performed as follows:

If a record is displayed in the form but is not being edited:

1. Calculate Global MetaScript,
2. Calculate variables,
3. Calculate dynamic popup contents and button availability.

If a record is being edited in the form (the "Edit" button has been clicked):

1. Calculate Global MetaScript,
2. Calculate variables and calculated fields,
3. Calculate dynamic popup contents and button availability.

If a new record is being added (i.e. the form is being loaded after being selected from the "New" drop-down menu):

1. Calculate Global MetaScript,
2. Calculate default values, variables, and calculated fields,
3. Calculate dynamic popup contents and button availability.