GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

42574258425942604261426242634264426542664267426842694270427142724273427442754276427742784279428042814282428342844285bit count by (1 plus the number of ‘0’ bits following the rightmost ‘1’ bit of that finalbyte).I.5.3 General description of ID valuesA registered data format defines (at a minimum) a Primary Base ID Table (a detailedspecification for registered ID tables may be found in Annex J). This base table definesthe data system Identifier(s) represented by each row of the table, any Secondary ID Bitsor Aux Format bits invoked by each table entry, and various implicit rules (taken from apredefined rule set) that decoding systems shall use when interpreting data encodedaccording to each entry. When a data item is encoded in a Packed Object, its associatedtable entry is identified by the entry’s relative position in the Base Table. This tableposition or index is the ID Value that is represented in Packed Objects.A Base Table containing a given number of entries inherently specifies the number of bitsneeded to encode a table index (i.e., an ID Value) in an ID List Packed Object (as the Log(base 2) of the number of entries). Since current and future data system ID Tables willvary in unpredictable ways in terms of their numbers of table entries, there is a need topre-define an ID Value Size mechanism that allows for future extensibility toaccommodate new tables, while minimizing decoder complexity and minimizing the needto upgrade decoding software (other than the addition of new tables). Therefore,regardless of the exact number of Base Table entries defined, each Base Table definitionshall utilize one of the predefined sizes for ID Value encodings defined in Table I 5-5(any unused entries shall be labeled as reserved, as provided in Annex J). The ID SizeBit pattern is encoded in a Packed Object only when it uses a non-default Base ID Table.Some entries in the table indicate a size that is not an integral power of two. Whenencoding (into an IDLPO) ID Values from tables that utilize such sizes, each pair of IDValues is encoded by multiplying the earlier ID of the pair by the base specified in thefourth column of Table I-5-5 and adding the later ID of the pair, and encoding the resultin the number of bits specified in the fourth column. If there is a trailing single ID Valuefor this ID Table, it is encoded in the number of bits specified in the third column ofTable I-5-5.Copyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 173 of 218