Change syntax to $epand=NavProp/$ref(<nested options>) and define a different set following $ref than the one directly following the navigation property: expand = '$expand' EQ expandItem *( COMMA expandItem ) expandItem = [ qualifiedEntityTypeName "/" ] navigationProperty [ "/" qualifiedEntityTypeName ] [ ref OPEN expandRefOption *( SEMI expandRefOption ) CLOSE / OPEN expandOption *( SEMI expandOption ) CLOSE ] expandRefOption = filter / search / skip / top / inlinecount expandOption = expandRefOption / select / orderby / expand / levels Rationale: we now express in the ABNF what is meaningful and thus allowed after /$ref. Also this allows parsing from left to right. And putting /$ref before the parens makes it a bit more obvious. Just try reading $expand=Items($filter=something very complicated and lengthy and I'll only tell you afterwards that I only want)/$ref&andsoon

https://tools.oasis-open.org/version-control/browse/wsvn/odata/trunk/spec/ABNF/odata-abnf-construction-rules-v4.0-wd01.txt?rev=253 https://tools.oasis-open.org/version-control/browse/wsvn/odata/trunk/spec/ABNF/odata-abnf-testcases.xml?rev=253 Accepted: https://www.oasis-open.org/committees/download.php/49055/odata-meeting-35_on-20130502-minutes.html#odata-345