ELF: Executable and Linkable Format
A symbol’s type provides a general classification for the associated entity.
Figure 1-18: Symbol Types, ELF32_ST_TYPE
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Value
_ _____________________
STT_NOTYPE
0
STT_OBJECT
1
STT_FUNC
2
STT_SECTION
3
STT_FILE
4
STT_LOPROC
13
STT_HIPROC
15
_ _____________________
?
?
?
?
?
?
?
?
?
STT_NOTYPE
The symbol’s type is not specified.
STT_OBJECT
The symbol is associated with a data object, such as a variable, an array, etc.
STT_FUNC
The symbol is associated with a function or other executable code.
STT_SECTION
The symbol is associated with a section. Symbol table entries of this type exist pri-
marily for relocation and normally have STB_LOCAL binding.
STT_FILE
Conventionally, the symbol’s name gives the name of the source file associated with the
object file. A file symbol has STB_LOCAL binding, its section index is SHN_ABS , and it
precedes the other STB_LOCAL symbols for the file, if it is present.
STT_LOPROC through STT_HIPROC
Values in this inclusive range are reserved for processor-specific semantics.
Function symbols (those with type STT_FUNC ) in shared object files have special significance. When
another object file references a function from a shared object, the link editor automatically creates a pro-
cedure linkage table entry for the referenced symbol. Shared object symbols with types other than
STT_FUNC will not be referenced automatically through the procedure linkage table.
If a symbol’s value refers to a specific location within a section, its section index member, st_shndx ,
holds an index into the section header table. As the section moves during relocation, the symbol’s value
changes as well, and references to the symbol continue to ”point” to the same location in the program.
Some special section index values give other semantics.
SHN_ABS
The symbol has an absolute value that will not change because of relocation.
SHN_COMMON
The symbol labels a common block that has not yet been allocated. The symbol’s value
gives alignment constraints, similar to a section’s sh_addralign member. That is, the
link editor will allocate the storage for the symbol at an address that is a multiple of
st_value . The symbol’s size tells how many bytes are required.
SHN_UNDEF
This section table index means t http://linux-miheeff.ru linux ??????? ??? windows

When my son was 12 weeks from conception, a doctor asked us if we wanted to check to see if he had down syndrome (or possibly other things) so we would still have the option to abort. I imagine that in 8 years people will start aborting left-handed or green eyed fetuses. It will certainly raise a lot of ethical issues. God help us if they find a “gay gene”.

Anyway, this is a cool article and biometrics are only at their beginnings. Soon the time will come when we live like in “demolition man”.

Actually there is still a growing IRIS picture base, which is told to be unique to each individual, just like fingerprints.

@Jamie – Oops, you’re right. I wonder how much data is in all that digestive-tract DNA. Also, 25 Megs doesn’t cover the information necessary to specify a human egg cell, or mitochondrial DNA. It also isn’t nearly enough to capture the full state of a human brain, so the people you could put on your iPod wouldn’t be your “friends” in any real sense, more like “clones of your friends.”

@Adam – Good article. I’m intrigued but remain a bit skeptical whether these services are worth anything near the cost. I hope to find out…

@EbilPhish – Woah.

http://www.creativetime.org/programs/archive/2000/DNAidBillboard/dnaid/copyright-instructions.html

http://www.guardian.co.uk/science/2008/jan/22/genetics.health

Only about 3% of all human DNA actually codes for proteins, and the rest is ignored and generally referred to as “junk DNA.”

Besides coding DNA and junk DNA, there is also regulatory DNA, which controls things like when coding DNA is active.

I can hardly wait until you can get your entire genome sequenced for a few thousand dollars.

PS Is there a way to make the submission not require JS? I use NoScript and ended up retyping my comment after granting temporary permissions.