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[90.03.05]
4. System References:
Each of these references is a 15-bit code. The high-order bits are used to distinguish between types of reference, while the low-order part of the field gives the reference number.
The reference type codes are:
0000 system reference (11-bit system reference number follows).
0001 file reference (11-bit file index number follows).
0010 ⎫
0011 ⎬ these codes are not assigned.
10 ⎭
11 external name table reference. This occurs only in 2TEXT, and is
followed by 13 bits giving the relative location of an entry in the
External Name Table during loading.
5.
The decrement or address, or both, of a data word can be represented by a complex expression. This expression consists of a string of one or more words, each with a corresponding control group, following the data word. If both the decrement and address are complex, the decrement occurs first.
Each word of a complex expression has the form
OP A,B,C
where
OP = PZE +
= PON -
= PTW *
= PTH /
The control group has the same form as that for a standard word, with the 11 code changed to mean a result storage cell. Six such result storages (0, 1, ..., 6) are used for intermediate results during the evaluation of a complex expression.
A word in a complex expression is to be interpreted as
A OP C --> B
where B is the result storage cell into which the result is to be placed. The complex expression is terminated by a word for which B = 7.