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CHAPTER 10                                                     Document Interchange



The unique name is formed by appending an encoded form of the page set’s digi-
tal identifier string to the original name of the destination or field. The identifier
string must be encoded to remove characters that have special meaning in desti-
nations and fields. For example, since the period character ( . ) is used as the field
separator in interactive form field names, it must not appear in the identifier por-
tion of the unique name; it is therefore encoded internally as two bytes, 92 and
112, corresponding to the ASCII characters \p . Note that since the backslash
character ( \ ) has special meaning for the syntax of string objects, it must be pre-
ceded by another backslash when written in the PDF file. For example, if the orig-
inal digital identifier string were
   alpha . beta

it would be encoded internally as
   alpha \ pbeta

and written in the PDF file as
   ( alpha \ \ pbeta )

Similarly, the null character (character code 0) is encoded internally as the two
bytes 92 and 48, corresponding to the ASCII characters \0. If the original digital
identifier string were
   alphaØbeta

(where Ø denotes the null character), it would be encoded internally as
   alpha \ 0beta

and written in the PDF file as
   ( alpha \ \ 0beta )

Finally, the backslash character itself is encoded internally as the two bytes 92 and
92, corresponding to the characters \\. In written form, each of these in turn
requires a preceding backslash. Thus, the digital identifier string
   alpha \ beta

would be encoded internally as
   alpha \ \ beta

and written in the PDF file as
   ( alpha \ \ \ \ beta )

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