[#node-CoinbaseTx-script_sig_prefix]
= xref:node.adoc[node]::xref:node/CoinbaseTx.adoc[CoinbaseTx]::script&lowbar;sig&lowbar;prefix
:relfileprefix: ../../
:mrdocs:

Prefix which needs to be placed at the beginning of the scriptSig&period; Clients may append extra data to this as long as the overall scriptSig size is 100 bytes or less, to avoid the block being rejected with &quot;bad&hyphen;cb&hyphen;length&quot; error&period; At heights &lt;&equals; 16 the BIP 34 height push is only one byte long, so clients must append at least one additional byte to meet the consensus minimum scriptSig length of two bytes&period;

== Synopsis

Declared in `&lt;node&sol;mining&lowbar;types&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:CScript.adoc[CScript] script&lowbar;sig&lowbar;prefix;
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== Description

Currently with BIP 34, the prefix is guaranteed to be less than 8 bytes, but future soft forks could require longer prefixes&period;


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