ECO {#architecture_eco}
ECO is the opening-classification layer. It has two public halves:
@ref architecture_eco_code "Code" maps ECO text such as B20 or C50a1 to a
compact numeric value, and @ref architecture_eco_book "Book" loads a Scid ECO
text file and classifies exact @ref scid::core::Position "Position" values.
@startuml eco-overview skinparam backgroundColor #FFFFFF skinparam shadowing false skinparam linetype ortho skinparam defaultFontName Cantarel skinparam defaultFontSize 10 skinparam roundcorner 8 skinparam Nodesep 68 skinparam Ranksep 54 skinparam ArrowColor #4B5563 skinparam RectangleBorderColor #6B7280 skinparam RectangleBackgroundColor #EEF2FF
left to right direction
rectangle "ECO text file" as File #EEF2FF
rectangle "ECO classification" as Eco #FFF7ED
rectangle "Code mapping" as Code #EEF2FF
rectangle "Position lookup" as Position #EEF2FF
rectangle "Opening line views" as Lines #EEF2FF
rectangle "Database metadata" as Metadata #EEF2FF
File -[hidden]right- Eco Eco -[hidden]right- Code Position -[hidden]right- Lines Lines -[hidden]right- Metadata Eco -[hidden]down- Lines
File --> Eco : loads Eco --> Code : parses / formats Position --> Eco : exact board Eco --> Lines : prefix rows Code --> Metadata : compact value @enduml
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@ref architecture_eco_code "Code" is the small value model. It preserves Scid's extended ECO forms, provides basic and extended display strings, expands prefixes to their final subcode, and reduces full codes to database-statistics buckets.
@ref architecture_eco_book "Book" is the classifier. It reads the ECO source file, replays each line from the standard starting position, stores the final compact board, and later answers exact-position lookups or prefix listings.
ECO touches Database at the metadata boundary. Database records carry a compact ECO classification for browsing, sorting, searching and statistics, while the ECO library supplies the public code vocabulary and the position classifier that can produce those classifications.