Here are some notes I took while reading the hledger manual from front to back.

My notes are divided into 2 sections. The first describes things pertinent to the current manifestation of hledger.

The second describes items I'd like to see added to hledger in support of the work on DEB2/DEA for Scientists.

Current Ideas for Hledger

• describe currency as commodity (doc) - see conversion & cost -  I like the definition of currency as being a type of commodity. Because it tends to have the same value over time it is a current commodity used in transactions.
• error in period documentation (doc) - "months" in SECTION "4.4.2 More complex report intervals" in example "-p "every 5 month from"
• add documentation enhancement (doc) - see add - under add it says "This is the only hledger command that writes to the journal file." but import writes to it as well, correct?
• revenue/expense (kudos) - I like your points that revenue and expenses are strictly speaking equity. They are things that come from and go to the environment
• equity conversions (kudos) - I also like the work done on equity conversions. Something I’ve not heard of before
• opening/closing commands (kudos) - I really like the opening and closing Commands. They are new for me.
• composed pivots (niceif) - It would be nice if pivot allowed multiple segments to be appended to one another, for example accounts and tags.
• com as synonym for cur (niceif) - see query types - I’d like to see "com:" (for commodities) as a synonym for "cur:" (see above)

Future ideas for a science-enabled Hledger

• Time of transactions ? (niceif) - see Dates - Would it be possible to support ISO8601 (or perhaps an "authorized" time tag for a transaction date syntax? It would be nice if time-periods were supports (ISO8601 already has this).
• Haskel for csvy processing (niceif) - csvy (https://csvy.org) is the file format I am considering for daybooks (an intermediate file between memoranda and journals). It would be nice if there was a haskel function that supported them.
• Commodity conversions based on things other than date (niceif) - see Declaring market prices - I am interested in P directives that support commodity conversion that are functions of characteristics other than %date. One example addresses how to support instrument calibrations that allow voltages to be converted into things like temperature, pressure, etc. in sensors. This would require a function based on the value being converted from volts to temp.
• Commodities with colons treated specially (niceif) - this needs a deeper discussion. It relates to the idea I use in my work is that the commodity is actually part of the account name. The feature I'd like to eventually see in the hledger ecosystem would be the ability to shift an hledger subaccount contents (including it's own subaccounts) from one account to another, as a "commodity".
• Possible to express point of view as hledger journal?? (thought) - I am wondering how much of a DEB2 point of view might be expressed in an hledger journal file. I'm encouraged by what I've read so far. Dictionaries including account, commodity, account, payee (as object being interacted with), tag (in future) declarations along with an updated form of commodity conversions is a great start!
• Ability to declare tags (niceif) - it would be nice to be able to declare tags in the same way that accounts, commodities are declared. Tags might have types. One type of tag that might be useful is a csv-type tag. The fields for this tag would be declared in a tag declaration. This tag would be useful because it would allow the csv record from which a journal entry was generated to be added as a comment but also interpretable.
• meaning: as a supported tag in declarations (niceif) - it would be nice to define a syntax for optionally declaring descriptive meanings for accounts, commodities, prices, and tags used in a journal. The syntax would support features such as types for commodities, tags, prices as is now supported for accounts.