Here is a list of all documented variables with links to the class documentation for each member:

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- u -

• udp_p2p_ : callProtocol
• udp_reflector_ : callProtocol
• unavailability_reason_ : availableReactions
• unclaimed_prize_count_ : messageGiveawayCompleted, messageGiveawayWinners
• unconfirmed_session_count_ : updateUnconfirmedSession
• unencrypted_prefix_size_ : encryptGroupCallData
• unique_gift_number_ : giftAuctionAcquiredGift, messageGift, receivedGift
• unique_id_ : call, groupCall, messageCall, messageGroupCall, remoteFile, sponsoredChat, videoMessageAdvertisement
• unix_time_ : richTextDateTime, textEntityTypeDateTime
• unlimited_gifts_ : acceptedGiftTypes
• unread_count_ : chat, directMessagesChatTopic, forumTopic, updateChatReadInbox, updateUnreadChatCount, updateUnreadMessageCount
• unread_mention_count_ : chat, forumTopic, updateChatUnreadMentionCount, updateForumTopic, updateMessageMentionRead
• unread_message_count_ : messageThreadInfo
• unread_poll_vote_count_ : chat, forumTopic, updateChatUnreadPollVoteCount, updateForumTopic, updateMessageContainsUnreadPollVotes
• unread_reaction_count_ : chat, directMessagesChatTopic, forumTopic, updateChatUnreadReactionCount, updateForumTopic, updateMessageUnreadReactions
• unread_reactions_ : message, updateMessageUnreadReactions
• unread_unmuted_count_ : updateUnreadChatCount, updateUnreadMessageCount
• unrestrict_boost_count_ : setSupergroupUnrestrictBoostCount, supergroupFullInfo
• update_order_of_installed_sticker_sets_ : messageSendOptions
• update_recent_reactions_ : addMessageReaction, setStoryReaction
• updates_ : updates
• upgrade_star_count_ : gift
• upgrade_variant_count_ : gift
• upgraded_from_basic_group_id_ : supergroupFullInfo
• upgraded_from_max_message_id_ : supergroupFullInfo
• upgraded_gift_colors_ : chat, updateChatAccentColors, user
• upgraded_gift_colors_id_ : setUpgradedGiftColors
• upgraded_gift_id_ : emojiStatusTypeUpgradedGift
• upgraded_gifts_ : acceptedGiftTypes
• upgraded_received_gift_id_ : messageGift
• upgraded_to_supergroup_id_ : basicGroup
• uploaded_size_ : remoteFile
• url_ : acceptOauthRequest, addWebBrowserSettingsException, advertisementSponsor, answerCallbackQuery, answerChatJoinRequestQuery, authenticationCodeTypeFragment, bankCardActionOpenUrl, botMenuButton, callbackQueryAnswer, checkOauthRequestMatchCode, checkWebAppFileDownload, collectibleItemInfo, connectedAffiliateProgram, declineOauthRequest, disconnectAffiliateProgram, getChatBoostLinkInfo, getMessageLinkInfo, getOauthLinkInfo, getWebAppUrl, getWebPageInstantView, httpUrl, inlineKeyboardButtonTypeLoginUrl, inlineKeyboardButtonTypeUrl, inlineKeyboardButtonTypeWebApp, inlineQueryResultArticle, inlineQueryResultsButtonTypeWebApp, inputInlineQueryResultArticle, inputPollMediaLink, inputStoryAreaTypeLink, internalLinkTypeAttachmentMenuBot, internalLinkTypeChatBoost, internalLinkTypeInstantView, internalLinkTypeMessage, internalLinkTypeOauth, keyboardButtonTypeWebApp, linkPreview, linkPreviewOptions, linkPreviewTypeEmbeddedAnimationPlayer, linkPreviewTypeEmbeddedAudioPlayer, linkPreviewTypeEmbeddedVideoPlayer, linkPreviewTypeExternalAudio, linkPreviewTypeExternalVideo, loginUrlInfoOpen, loginUrlInfoRequestConfirmation, mainWebApp, oauthLinkInfo, openWebApp, pageBlockEmbedded, pageBlockEmbeddedPost, pageBlockPhoto, pageBlockRelatedArticle, paymentOption, paymentProviderOther, pollMediaLink, removeWebBrowserSettingsException, revenueWithdrawalStateSucceeded, richTextAnchorLink, richTextReferenceLink, richTextUrl, rtmpUrl, storyAreaTypeLink, suggestedActionCustom, textEntityTypeTextUrl, tMeUrl, updateNewOauthRequest, userLink, webAppInfo, webAppUrl, webDomainException
• urls_ : tMeUrls
• usd_rate_ : chatRevenueStatistics, gramRevenueStatistics, starRevenueStatistics
• use_chat_info_database_ : setTdlibParameters
• use_date_ : premiumGiftCodeInfo
• use_default_disable_mention_notifications_ : chatNotificationSettings
• use_default_disable_pinned_message_notifications_ : chatNotificationSettings
• use_default_mute_for_ : chatNotificationSettings
• use_default_mute_stories_ : chatNotificationSettings, scopeNotificationSettings
• use_default_show_preview_ : chatNotificationSettings
• use_default_show_story_poster_ : chatNotificationSettings
• use_default_sound_ : chatNotificationSettings
• use_default_story_sound_ : chatNotificationSettings
• use_file_database_ : setTdlibParameters
• use_less_data_for_calls_ : autoDownloadSettings
• use_message_database_ : setTdlibParameters
• use_portrait_orientation_ : startGroupCallRecording
• use_secret_chats_ : setTdlibParameters
• use_test_dc_ : setTdlibParameters
• used_sender_id_ : messageReaction
• used_theme_chat_id_ : upgradedGift
• user_ : updateUser
• user_administrator_rights_ : keyboardButtonTypeRequestChat
• user_bid_ : auctionStateActive
• user_chat_id_ : businessConnection, updateNewChatJoinRequest
• user_count_ : connectedAffiliateProgram
• user_country_code_ : giveawayParticipantStatusDisallowedCountry
• user_full_info_ : updateUserFullInfo
• user_handle_ : checkAuthenticationPasskey
• user_id_ : addChatMember, addContact, addStickerToSet, affiliateTypeBot, allowUnpaidMessagesFromUser, botCommandScopeChatMember, businessConnection, call, canSendMessageToUser, chatAdministrator, chatBoostSourceGiftCode, chatBoostSourceGiveaway, chatBoostSourcePremium, chatEventMemberInvited, chatEventMemberPromoted, chatEventMemberSubscriptionExtended, chatEventMemberTagChanged, chatInviteLinkCount, chatInviteLinkMember, chatJoinRequest, chatRevenueTransactionTypeSuggestedPostEarnings, chatStatisticsAdministratorActionsInfo, chatStatisticsInviterInfo, chatStatisticsMessageSenderInfo, chatTypePrivate, chatTypeSecret, closeBirthdayUser, contact, createCall, createNewSecretChat, createNewStickerSet, createPrivateChat, editUserStarSubscription, failedToAddMember, gameHighScore, getGameHighScores, getGroupsInCommon, getInlineGameHighScores, getMenuButton, getPaidMessageRevenue, getPersonalChatHistory, getStarGiftPaymentOptions, getUser, getUserChatBoosts, getUserFullInfo, getUserProfileAudios, getUserProfilePhotos, getUserSupportInfo, giftPremiumWithStars, inlineKeyboardButtonTypeUser, inviteGroupCallParticipant, messageChatDeleteMember, messageSenderUser, messageViewer, oauthLinkInfo, placeGiftAuctionBid, premiumGiftCodeInfo, processChatJoinRequest, refundStarPayment, replaceStickerInSet, richTextMentionName, savePreparedInlineMessage, savePreparedKeyboardButton, secretChat, setChatMemberTag, setGameScore, setInlineGameScore, setMenuButton, setPassportElementErrors, setStickerSetThumbnail, setUserEmojiStatus, setUserNote, setUserPersonalProfilePhoto, setUserSupportInfo, sharedUser, sharePhoneNumber, starTransactionTypeBotInvoicePurchase, starTransactionTypeBotInvoiceSale, starTransactionTypeBotPaidMediaPurchase, starTransactionTypeBotPaidMediaSale, starTransactionTypeBotSubscriptionPurchase, starTransactionTypeBotSubscriptionSale, starTransactionTypeBusinessBotTransferReceive, starTransactionTypeBusinessBotTransferSend, starTransactionTypeChannelPaidMediaSale, starTransactionTypeChannelPaidReactionReceive, starTransactionTypeChannelSubscriptionSale, starTransactionTypeGiftSale, starTransactionTypeGiftUpgrade, starTransactionTypePremiumPurchase, starTransactionTypeSuggestedPostPaymentReceive, starTransactionTypeUpgradedGiftPurchase, starTransactionTypeUpgradedGiftSale, starTransactionTypeUserDeposit, storePaymentPurposeGiftedStars, storePaymentPurposePremiumGift, suggestUserBirthdate, suggestUserProfilePhoto, telegramPaymentPurposeGiftedStars, telegramPaymentPurposePremiumGift, textEntityTypeMentionName, tMeUrlTypeUser, tonTransactionTypeUpgradedGiftPurchase, tonTransactionTypeUpgradedGiftSale, transferChatOwnership, updateManagedBot, updatePaidMediaPurchased, updateUserFullInfo, updateUserStatus, updateUserSubscription, uploadStickerFile
• user_ids_ : addChatMembers, banGroupCallParticipants, chatJoinRequestsInfo, createNewBasicGroupChat, foundUsers, getChatEventLog, importedContacts, inviteVideoChatParticipants, messageInviteVideoChatParticipants, removeContacts, setCloseFriends, storePaymentPurposePremiumGiftCodes, storyPrivacySettingsSelectedUsers, telegramPaymentPurposePremiumGiftCodes, userPrivacySettingRuleAllowUsers, userPrivacySettingRuleRestrictUsers, users
• user_is_bot_ : keyboardButtonTypeRequestUsers
• user_is_premium_ : keyboardButtonTypeRequestUsers
• user_limits_ : gift
• user_location_ : getInlineQueryResults, updateNewChosenInlineResult, updateNewInlineQuery
• username_ : callServerTypeWebrtc, checkBotUsername, checkChatUsername, collectibleItemTypeUsername, createBot, internalLinkTypeChatAffiliateProgram, pageBlockChatLink, proxyTypeHttp, proxyTypeSocks5, richTextMention, searchChatAffiliateProgram, searchPublicChat, setBusinessAccountUsername, setSupergroupUsername, setUsername, sharedChat, sharedUser, toggleBotUsernameIsActive, toggleSupergroupUsernameIsActive, toggleUsernameIsActive
• usernames_ : reorderActiveUsernames, reorderBotActiveUsernames, reorderSupergroupActiveUsernames, supergroup, user
• users_ : messageUsersShared
• uses_unofficial_app_ : userFullInfo
• utc_time_offset_ : timeZone
• utility_bill_ : inputPassportElementUtilityBill, passportElementUtilityBill