Global settings can affect scheduling in two ways—the Time Periods setting in the Application section of the Administer menu, and the associated calendar setting Use assigned calendar to specify the number of work hours for each time period.
These values are a sort of default for the program to identify how many units (hours) are equivalent to a day when calculating duration from the standard equation (Duration = Units / Units per Time). Other equal values are defined here, such as hours in a week, hours in a month, and hours in a year. This becomes important at the activity level because P6 actually stores the duration as hours and displays the duration according to the calculations of a standard day. Likewise, if you enter an activity's duration as 2w, Primavera will use the same settings to convert to the appropriate number of days/hours.
Using the sample settings shown (8.0 as Hours/Day); a user could enter 1d (one day) as the duration on an activity and the...