Determine the source of the following data by indicating $l$ for the part drawing, 2 for the production plan, and 3 for additional instructions.
a. Time allocation
b. Overall size and shape of the part
c. Required accuracy
d. Sequence of operations
e. Type and size of machines used
f. Money available
g. Number of pieces
h. Previous machining
i. Locating surfaces
j. Material specifications
k. Type of cutters needed
l. Type of machining required