NOT 4,294,967,295 as stated earlier which left out the zero value.

/* tips_int_range.p */
/* count valid unique numbers that can be placed into an integer data type */

def var a_int_32 as int no-undo.
def var b_int_64 as int64 no-undo.

/* ————————————————————————- */
/* maximum integer unique numbers */
/* ————————————————————————- */
Evaluate_Integer:
do while true.
/* ————————————————————————- */
/* maximum integer unique numbers */
/* ————————————————————————- */
a_int_32 = 0 no-error.
if error-status:error then
leave Evaluate_Integer.
else
b_int_64 = 1. /* count zero value */

/* ————————————————————————- */
/* compute number of positive unique numbers */
/* ————————————————————————- */
assign
a_int_32 = 2147483646 /* maximum (2147483647) - 1 */
b_int_64 = b_int_64 + a_int_32.

EI_Positive:
do while true:
a_int_32 = a_int_32 + 1 no-error.
if error-status:error then
leave EI_Positive.
else
b_int_64 = b_int_64 + 1. /* count positive value */
end.

/* ————————————————————————- */
/* compute number of negative unique numbers */
/* ————————————————————————- */
assign
a_int_32 = -2147483647 /* minimum (-2147483648) + 1 */
b_int_64 = b_int_64 + abs(a_int_32).

EI_Negative:
do while true:
a_int_32 = a_int_32 - 1 no-error.
if error-status:error then
leave EI_Negative.
else
b_int_64 = b_int_64 + 1. /* count negative value */
end.

leave Evaluate_Integer.
end.

/* ————————————————————————- */
/* display maximum */
/* ————————————————————————- */
display b_int_64 format “->,>>>,>>>,>>9″
label “Integer (32) Capacity”.

/* tips_unknown.p */
/* the unknown value is not a value at all */

def var a_unknown as char no-undo.
def var b_num_len as int no-undo.
def var c_num_asc as int no-undo.
def var d_str_sub as char no-undo.

assign
a_unknown = ?
b_num_len = 123.

assign
b_num_len = length(a_unknown).
c_num_asc = asc(a_unknown).
d_str_sub = substring(a_unknown,1,1).

display
a_unknown label “unknown”
b_num_len label “length”
c_num_asc label “ASC value”
d_str_sub label “1st character”.

To prove this an integer in Progress is a 32 bit (4 bytes) signed numeric field where the number of unique values = 4,294,967,295.

See: http://oiswww.eumetsat.org/WEBOPS/eps-pg/Common/EPS-PG-A4EPSNativeFormatDataTypes.htm

This program illustrates that every single bit combination for the Progress Integer data type is used for a valid number yet it still can be represented by the unknown value.

/* tips_int_range.p */
/* count valid unique numbers that can be placed into an integer data type */

def var a_int_32 as int no-undo.
def var b_int_64 as int64 no-undo.

Evaluate_Integer:
do while true.
a_int_32 = 0 no-error.
if error-status:error then
leave Evaluate_Integer.
else
b_int_64 = 1. /* count zero value */

EI_Positive:
do while true:
a_int_32 = a_int_32 + 1 no-error.
if error-status:error then
leave EI_Positive.
else
b_int_64 = b_int_64 + 1. /* count positive value */
end.

a_int_32 = 0.

EI_Negative:
do while true:
a_int_32 = a_int_32 - 1 no-error.
if error-status:error then
leave EI_Negative.
else
b_int_64 = b_int_64 + 1. /* count negative value */
end.
end.

display b_int_64 format “->,>>>,>>>,>>9″
label “Integer (32) Capacity”.

Therefore, the Progress unknown value is not a value but an attribute or state of the field.

How Progress “stores” this “unknown value” in a database or in memory is still a mystery.

As far as there being an anomaly there is none.