6 Logical Model

11.113GPPRelease 1999Specification of the Subscriber Identity Module - Mobile Equipment (SIM-ME) InterfaceTS

This clause describes the logical structure for a SIM, the code associated with it, and the structure of files used.

6.1 General description

Figure 3 shows the general structural relationships which may exist between files. The files are organized in a hierarchical structure and are of one of three types as defined below. These files may be either administrative or application specific. The operating system handles the access to the data stored in different files.

MF

DF2

EF

DF1

DF11

DF111

EF

DF12

….

EF

EF

EF

EF

EF

….

Figure 3: Organization of memory

Files are composed of a header, which is internally managed by the SIM, and optionally a body part. The information of the header is related to the structure and attributes of the file and may be obtained by using the commands GET RESPONSE or STATUS. This information is fixed during the administrative phase. The body part contains the data of the file.

6.2 File identifier

A file ID is used to address or identify each specific file. The file ID consists of two bytes and shall be coded in hexadecimal notation. They are specified in clause 10.

The first byte identifies the type of file, and for GSM is:

‑ ‘3F’: Master File;

‑ ‘7F’: 1st level Dedicated File;

– ‘5F’: 2nd level Dedicated File;

‑ ‘2F’: Elementary File under the Master File;

‑ ‘6F’: Elementary File under a 1st level Dedicated File;

– ‘4F’: Elementary File under 2nd level Dedicated File.

File IDs shall be subject to the following conditions:

‑ the file ID shall be assigned at the time of creation of the file concerned;

‑ no two files under the same parent shall have the same ID;

‑ a child and any parent, either immediate or remote in the hierarchy, e.g. grandparent, shall never have the same file ID.

In this way each file is uniquely identified.

6.3 Dedicated files

A Dedicated File (DF) is a functional grouping of files consisting of itself and all those files which contain this DF in their parental hierarchy (that is to say it consists of the DF and its complete "subtree"). A DF "consists" only of a header part.

Four 1st level DFs are defined in this specification:

‑ DFGSM which contains the applications for both GSM and/or DCS 1800;

‑ DFIS41 which contains the applications for IS-41 as specified by ANSI T1P1;

‑ DFTELECOM which contains telecom service features;

– DFFP-CTS which contains the applications for the CTS fixed part (see TS 11.19 [34]).

All four files are immediate children of the Master File (MF) and may coexist on a multi‑application card.

2nd level DFs are defined in this specification under DFGSM.

All 2nd level DFs are immediate children of the DFGSM and may coexist on a multi-application card.

6.4 Elementary files

An Elementary File (EF) is composed of a header and a body part. The following three structures of an EF are used by GSM.

A file is associated with attributes that depending of the file type indicates how data is to be accessed e.g. file size, record length etc. Although in the present document some files and data structures stored in a file are indicated as having a fixed length; when reading such structures the terminal shall derive the length of the structure from the attributes provided in the file information i.e. not use the fixed value specified for the file in the present document. Although the terminal is able to read the entire structure it should only use those elements from the structure which is recognised by the terminal.

6.4.1 Transparent EF

An EF with a transparent structure consists of a sequence of bytes. When reading or updating, the sequence of bytes to be acted upon is referenced by a relative address (offset), which indicates the start position (in bytes), and the number of bytes to be read or updated. The first byte of a transparent EF has the relative address ’00 00′. The total data length of the body of the EF is indicated in the header of the EF.

Header

Body

Sequence
of bytes

NOTE: This structure was previously referred to as "binary" in GSM.

Figure 4: Structure of a transparent EF

6.4.2 Linear fixed EF

An EF with linear fixed structure consists of a sequence of records all having the same (fixed) length. The first record is record number 1. The length of a record as well as this value multiplied by the number of records are indicated in the header of the EF.

Header

Body

Record 1

Record 2

:

:

Record n

Figure 5: Structure of a linear fixed file

There are several methods to access records within an EF of this type:

‑ absolutely using the record number;

‑ when the record pointer is not set it shall be possible to perform an action on the first or the last record by using the NEXT or PREVIOUS mode;

‑ when the record pointer is set it shall be possible to perform an action on this record, the next record (unless the record pointer is set to the last record) or the previous record (unless the record pointer is set to the first record);

‑ by identifying a record using pattern seek starting:

‑ forwards from the beginning of the file;

‑ forwards from the record following the one at which the record pointer is set (unless the record pointer is set to the last record);

‑ backwards from the end of the file;

‑ backwards from the record preceding the one at which the record pointer is set (unless the record pointer is set to the first record).

If an action following selection of a record is aborted, then the record pointer shall remain set at the record at which it was set prior to the action. According to ISO/IEC 7816-4 [35] it is not possible to have more than 254 records in a file of this type, and each record can not be more than 255 bytes using the short command APDU format.

NOTE: This structure was previously referred to as "formatted" in GSM.

6.4.3 Cyclic EF

Cyclic files are used for storing records in chronological order. When all records have been used for storage, then the next storage of data shall overwrite the oldest information.

An EF with a cyclic structure consists of a fixed number of records with the same (fixed) length. In this file structure there is a link between the last record (n) and the first record. When the record pointer is set to the last record n, then the next record is record 1. Similarly, when the record pointer is set to record 1, then the previous record is record n. The last updated record containing the newest data is record number 1, and the oldest data is held in record number n.

Header

Body

Record 1

Record 2

:

:

Record n

Figure 6: Structure of a cyclic file

For update operations only PREVIOUS record shall be used. For reading operations, the methods of addressing are Next, Previous, Current and Record Number.

After selection of a cyclic file (for either operation), the record pointer shall address the record updated or increased last. If an action following selection of a record is aborted, then the record pointer shall remain set at the record at which it was set prior to the action.

NOTE: It is not possible, at present, to have more than 255 records in a file of this type, and each record cannot be greater than 255 bytes.

6.5 Methods for selecting a file

After the Answer To Reset (ATR), the Master File (MF) is implicitly selected and becomes the Current Directory. Each file may then be selected by using the SELECT function in accordance with the following rules.

Selecting a DF or the MF sets the Current Directory. After such a selection there is no current EF. Selecting an EF sets the current EF and the Current Directory remains the DF or MF which is the parent of this EF. The current EF is always a child of the Current Directory.

Any application specific command shall only be operable if it is specific to the Current Directory.

The following files may be selected from the last selected file:

‑ any file which is an immediate child of the Current Directory;

‑ any DF which is an immediate child of the parent of the current DF;

‑ the parent of the Current Directory;

‑ the current DF;

‑ the MF.

This means in particular that a DF shall be selected prior to the selection of any of its EFs. All selections are made using the file ID.

The following figure gives the logical structure for the GSM application. GSM defines only two levels of DFs under the MF.

Figure 7: Logical structure

The following table gives the valid selections for GSM for the logical structure in figure 7. Reselection of the last selected file is also allowed but not shown.

Table 6: File selection

Last selected file

Valid Selections

MF

DF1, DF2, EF1

DF1

MF, DF2, DF3, EF2

DF2

MF, DF1, EF3, EF4

DF3

MF, DF1, EF5

EF1

MF, DF1, DF2

EF2

MF, DF1, DF2, DF3

EF3

MF, DF1, DF2, EF4

EF5

MF, DF1, DF3

6.6 Reservation of file IDs

In addition to the identifiers used for the files specified in the present document, the following file IDs are reserved for use by GSM.

Dedicated Files:

‑ administrative use:

‘7F 4X’, ‘5F1X’, ‘5F2X’

‑ operational use:

‘7F 10’ (DFTELECOM), ‘7F 20’ (DFGSM), ‘7F 21’ (DFDCS1800), ‘7F 22’ (DFIS-41), ‘7F 23’ (DFFP-CTS) (see TS 11.19 [34]), ‘7F 24’ (DFTIA/EIA-136), ‘7F 25’ (DFTIA/EIA-95), and ‘7F 2X’, where X ranges from ‘6’ to ‘F’.

NOTE: ‘7F 80’ (DFPDC) is used in the Japanese PDC specification.
‘7F 90’ (DFTETRA) is used in the ETSI TETRA specification [44]
‘7F 31’ (DFiDEN) is used in the iDEN specification.

– reserved under ‘7F10’:

‘5F50’ (DFGRAPHICS)

– reserved under ‘7F20’:

‘5F30’ (DFIRIDIUM), ‘5F31’ (DFGlobalstar), ‘5F32’ (DFICO), ‘5F33’ (DFACeS), ‘5F3C’ (DFMExE), ‘5F3X’, where X ranges from ‘4’ to ‘B’ and ‘D’ to ‘F’;

‘5F40′(DFEIA/TIA-553), ‘5F4Y’ where Y ranges from ‘1’ to ‘F’;

‘5F5X’ where X ranges from ‘0’ to ‘F’;

‘5F60′(DFCTS), ‘5F6Y’ where Y ranges from ‘1’ to ‘F’;

‘5F70’ (DFSoLSA), ‘5F7Y’ where Y ranges from ‘1’ to ‘F’;

‘5FYX’ where Y ranges from ‘8’ to ‘F’ and X from ‘0’ to ‘F’.

Elementary files:

‑ administrative use:

‘6F XX’ in the DFs ‘7F 4X’; ‘4F XX’ in the DFs ‘5F 1X’, ‘5F2X’

‘6F 1X’ in the DFs ‘7F 10’, ‘7F 20’, ‘7F 21’;

‘4F 1X’ in all 2nd level DFs

‘2F 01’, ‘2F EX’ in the MF ‘3F 00’;

‑ operational use:

‘6F 2X’, ‘6F 3X’, ‘6F 4X’ in ‘7F 10’ and ‘7F 2X’;

‘4F YX’, where Y ranges from ‘2’ to ‘F’ in all 2nd level DFs.

‘2F 1X’ in the MF ‘3F 00’.

In all the above, X ranges, unless otherwise stated, from ‘0’ to ‘F’.