This attribute is only relevant for HW Compression VCs
configured for CPC, 8K history. It indicates the Search
Depth configured for this line. Increasing this attribute
may allow the user to achieve better Compression ratios.
This however could occur at the expense of throughput
(i.e. you may get better compression ratios, but lower
throughput). Note that this value may be set to 0, if the
user wishes to run their Line in High Speed mode.